Hi Pedro

On Fri, Aug 30, 2024 at 5:45 AM Pedro Falcato pedro.falcato@gmail.com wrote:

On Thu, Aug 29, 2024 at 09:43:49PM GMT, jeffxu@chromium.org wrote:

...

From: Jeff Xu jeffxu@chromium.org

Add check for vma size, prot bits and error return.

Signed-off-by: Jeff Xu jeffxu@chromium.org

tools/testing/selftests/mm/mseal_test.c | 398 ++++++++++++++++++++---- 1 file changed, 332 insertions(+), 66 deletions(-)

diff --git a/tools/testing/selftests/mm/mseal_test.c b/tools/testing/selftests/mm/mseal_test.c index e7991e5fdcf3..adc646cf576c 100644 --- a/tools/testing/selftests/mm/mseal_test.c +++ b/tools/testing/selftests/mm/mseal_test.c @@ -170,18 +170,31 @@ static void set_pkey(int pkey, unsigned long pkey_value) static void setup_single_address(int size, void **ptrOut) { void *ptr;

• unsigned long page_size = getpagesize();
  
  

• ptr = mmap(NULL, size, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
  

• *ptrOut = ptr;
  

• *ptrOut = (void *)-1;
  

• ptr = mmap(NULL, size + 2 * page_size, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
  

• if (ptr != (void *) -1) {
  

MAP_FAILED, not (void *) -1

ok.

...

•         /* add 2 page at the beginning and end to avoid auto-merge of mapping */
  

•         sys_mprotect(ptr, page_size, PROT_NONE);
  

•         sys_mprotect(ptr + size + page_size, page_size, PROT_NONE);
  

•         *ptrOut = ptr + page_size;
  

• }
  

}

static void setup_single_address_rw(int size, void **ptrOut) { void *ptr; unsigned long mapflags = MAP_ANONYMOUS | MAP_PRIVATE;

• unsigned long page_size = getpagesize();
  
  

• ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, mapflags, -1, 0);
  

• *ptrOut = ptr;
  

• *ptrOut = (void *)-1;
  

• ptr = mmap(NULL, size + 2 * page_size, PROT_READ | PROT_WRITE, mapflags, -1, 0);
  

• if (ptr != (void *) -1) {
  

Same here.

ok.

...

•         sys_mprotect(ptr, page_size, PROT_NONE);
  

•         sys_mprotect(ptr + size + page_size, page_size, PROT_NONE);
  

•         *ptrOut = ptr + page_size;
  

• }
  

}

static int clean_single_address(void *ptr, int size) @@ -226,6 +239,21 @@ bool pkey_supported(void) return false; }

+bool get_vma_size_supported(void) +{

• void *ptr;
  

• unsigned long page_size = getpagesize();
  

• unsigned long size = 4 * page_size;
  

• int prot;
  

• setup_single_address(size, &ptr);
  

• size = get_vma_size(ptr, &prot);
  

• if (size == 4 * page_size && prot == 0x4)
  

•         return true;
  

• return false;
  

+}

static void test_seal_addseal(void) { int ret; @@ -419,11 +447,17 @@ static void test_seal_invalid_input(void) unsigned long size = 4 * page_size; int ret;

• setup_single_address(8 * page_size, &ptr);
  

• setup_single_address(9 * page_size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

• ret = clean_single_address(ptr + 4 * page_size, 4 * page_size);
  

• ret = clean_single_address(ptr, page_size);
  FAIL_TEST_IF_FALSE(!ret);
  
  

• ret = clean_single_address(ptr + 5 * page_size, 4 * page_size);
  

• FAIL_TEST_IF_FALSE(!ret);
  

• ptr = ptr + page_size;
  

• /* invalid flag */
  ret = syscall(__NR_mseal, ptr, size, 0x20);
  FAIL_TEST_IF_FALSE(ret < 0);
  

@@ -523,6 +557,7 @@ static void test_seal_mprotect(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -533,9 +568,14 @@ static void test_seal_mprotect(bool seal) }

  ret = sys_mprotect(ptr, size, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -547,6 +587,7 @@ static void test_seal_start_mprotect(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -558,9 +599,14 @@ static void test_seal_start_mprotect(bool seal)

  /* the first page is sealed. */
  ret = sys_mprotect(ptr, page_size, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  /* pages after the first page is not sealed. */
  

@@ -577,6 +623,7 @@ static void test_seal_end_mprotect(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -593,9 +640,14 @@ static void test_seal_end_mprotect(bool seal) /* last 3 page are sealed */ ret = sys_mprotect(ptr + page_size, page_size * 3, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr + page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -607,6 +659,7 @@ static void test_seal_mprotect_unalign_len(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -618,9 +671,14 @@ static void test_seal_mprotect_unalign_len(bool seal)

  /* 2 pages are sealed. */
  ret = sys_mprotect(ptr, page_size * 2, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  ret = sys_mprotect(ptr + page_size * 2, page_size,
  

@@ -636,6 +694,7 @@ static void test_seal_mprotect_unalign_len_variant_2(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -646,9 +705,14 @@ static void test_seal_mprotect_unalign_len_variant_2(bool seal)

  /* 3 pages are sealed. */
  ret = sys_mprotect(ptr, page_size * 3, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  ret = sys_mprotect(ptr + page_size * 3, page_size,
  

@@ -664,6 +728,7 @@ static void test_seal_mprotect_two_vma(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -678,16 +743,26 @@ static void test_seal_mprotect_two_vma(bool seal) }

  ret = sys_mprotect(ptr, page_size * 2, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x6);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  ret = sys_mprotect(ptr + page_size * 2, page_size * 2,
                  PROT_READ | PROT_WRITE);
  

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr + page_size * 2, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -699,6 +774,7 @@ static void test_seal_mprotect_two_vma_with_split(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -719,17 +795,27 @@ static void test_seal_mprotect_two_vma_with_split(bool seal)

  /* the second page is sealed. */
  ret = sys_mprotect(ptr + page_size, page_size, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x6);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  /* the third page is sealed. */
  ret = sys_mprotect(ptr + 2 * page_size, page_size,
                  PROT_READ | PROT_WRITE);
  

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr + 2 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  /* the fouth page is not sealed. */
  

@@ -746,6 +832,7 @@ static void test_seal_mprotect_partial_mprotect(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -758,9 +845,14 @@ static void test_seal_mprotect_partial_mprotect(bool seal)

  /* mprotect first 2 page will fail, since the first page are sealed. */
  ret = sys_mprotect(ptr, 2 * page_size, PROT_READ | PROT_WRITE);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -783,15 +875,15 @@ static void test_seal_mprotect_partial_mprotect_tail(bool seal) }

  ret = sys_mprotect(ptr, size, PROT_EXEC);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(!ret);
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  
  

• if (seal) {
  

•         FAIL_TEST_IF_FALSE(get_vma_size(ptr + page_size, &prot) > 0);
  

•         size = get_vma_size(ptr + page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
          FAIL_TEST_IF_FALSE(prot == 0x4);
  

• }
  

• } else
  

•         FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

} @@ -846,6 +938,7 @@ static void test_seal_mprotect_split(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -862,16 +955,34 @@ static void test_seal_mprotect_split(bool seal)

  /* mprotect is sealed. */
  ret = sys_mprotect(ptr, 2 * page_size, PROT_READ);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x6);
  

•         size = get_vma_size(ptr + page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  
  ret = sys_mprotect(ptr + 2 * page_size, 2 * page_size, PROT_READ);
  

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x6);
  

•         size = get_vma_size(ptr + page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -883,6 +994,7 @@ static void test_seal_mprotect_merge(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -899,9 +1011,18 @@ static void test_seal_mprotect_merge(bool seal)

  /* 2 pages are sealed. */
  ret = sys_mprotect(ptr, 2 * page_size, PROT_READ);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x6);
  

•         size = get_vma_size(ptr + page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  /* last 2 pages are not sealed. */
  

@@ -917,6 +1038,7 @@ static void test_seal_munmap(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -928,9 +1050,14 @@ static void test_seal_munmap(bool seal)

  /* 4 pages are sealed. */
  ret = sys_munmap(ptr, size);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -948,6 +1075,7 @@ static void test_seal_munmap_two_vma(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -962,15 +1090,33 @@ static void test_seal_munmap_two_vma(bool seal) }

  ret = sys_munmap(ptr, page_size * 2);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x6);
  

•         size = get_vma_size(ptr + 2 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  ret = sys_munmap(ptr + page_size, page_size * 2);
  

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x6);
  

•         size = get_vma_size(ptr + 2 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -1018,33 +1164,75 @@ static void test_seal_munmap_partial_across_vmas(bool seal) { void *ptr; unsigned long page_size = getpagesize();

• unsigned long size = 2 * page_size;
  

• unsigned long size = 12 * page_size;
  int ret;
  int prot;
  
  

• /*
  

•  * Check if a partial mseal (that results in two vmas) works correctly.
  

•  * It might unmap the first, but it'll never unmap the second (msealed) vma.
  

•  */
  

• setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  
  if (seal) {
  

•         ret = sys_mseal(ptr + page_size, page_size);
  

•         ret = sys_mseal(ptr + 4 * page_size, 4 * page_size);
          FAIL_TEST_IF_FALSE(!ret);
  }
  
  

• ret = sys_munmap(ptr, size);
  

• if (seal)
  

• ret = sys_munmap(ptr, 12 * page_size);
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 4 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 8 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  

• ret = sys_munmap(ptr, 6 * page_size);
  if (seal) {
  

•         FAIL_TEST_IF_FALSE(get_vma_size(ptr + page_size, &prot) > 0);
  

•         FAIL_TEST_IF_FALSE(ret < 0);
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 4 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
          FAIL_TEST_IF_FALSE(prot == 0x4);
  

• }
  

•         size = get_vma_size(ptr + 8 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
  

•         FAIL_TEST_IF_FALSE(!ret);
  

• ret = sys_munmap(ptr + 6 * page_size, 6 * page_size);
  

• if (seal) {
  

•         FAIL_TEST_IF_FALSE(ret < 0);
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 4 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 8 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
  

•         FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

} @@ -1074,9 +1262,11 @@ static void test_munmap_start_freed(bool seal) ret = sys_munmap(ptr, size); if (seal) { FAIL_TEST_IF_FALSE(ret < 0);

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  
          size = get_vma_size(ptr + page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == page_size * 3);
  

•         FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else {
          /* note: this will be OK, even the first page is */
          /* already unmapped. */
  

@@ -1095,6 +1285,7 @@ static void test_munmap_end_freed(bool seal) unsigned long page_size = getpagesize(); unsigned long size = 4 * page_size; int ret;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1111,9 +1302,14 @@ static void test_munmap_end_freed(bool seal)

  /* unmap all pages. */
  ret = sys_munmap(ptr, size);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  REPORT_TEST_PASS();
  

@@ -1144,12 +1340,15 @@ static void test_munmap_middle_freed(bool seal) ret = sys_munmap(ptr, size); if (seal) { FAIL_TEST_IF_FALSE(ret < 0);

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  
          size = get_vma_size(ptr, &prot);
          FAIL_TEST_IF_FALSE(size == page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  
          size = get_vma_size(ptr + page_size * 3, &prot);
          FAIL_TEST_IF_FALSE(size == page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else {
          FAIL_TEST_IF_FALSE(!ret);
  
  

@@ -1170,6 +1369,7 @@ static void test_seal_mremap_shrink(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1184,6 +1384,10 @@ static void test_seal_mremap_shrink(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == (void *) MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else {
          FAIL_TEST_IF_FALSE(ret2 != (void *) MAP_FAILED);
  
  

@@ -1199,6 +1403,7 @@ static void test_seal_mremap_expand(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1216,6 +1421,10 @@ static void test_seal_mremap_expand(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else {
          FAIL_TEST_IF_FALSE(ret2 == ptr);
  
  

@@ -1231,6 +1440,7 @@ static void test_seal_mremap_move(bool seal) unsigned long size = page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1249,10 +1459,12 @@ static void test_seal_mremap_move(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

• } else {
  

•         FAIL_TEST_IF_FALSE(ret2 != MAP_FAILED);
  
  

• }
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size ==  page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
  

•         FAIL_TEST_IF_FALSE(ret2 != MAP_FAILED);
  
  REPORT_TEST_PASS();
  

} @@ -1264,6 +1476,7 @@ static void test_seal_mmap_overwrite_prot(bool seal) unsigned long size = page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1279,6 +1492,10 @@ static void test_seal_mmap_overwrite_prot(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else
          FAIL_TEST_IF_FALSE(ret2 == ptr);
  
  

@@ -1292,6 +1509,7 @@ static void test_seal_mmap_expand(bool seal) unsigned long size = 12 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1310,6 +1528,10 @@ static void test_seal_mmap_expand(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 8 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else
          FAIL_TEST_IF_FALSE(ret2 == ptr);
  
  

@@ -1323,6 +1545,7 @@ static void test_seal_mmap_shrink(bool seal) unsigned long size = 12 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1338,6 +1561,10 @@ static void test_seal_mmap_shrink(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 12 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else
          FAIL_TEST_IF_FALSE(ret2 == ptr);
  
  

@@ -1352,6 +1579,7 @@ static void test_seal_mremap_shrink_fixed(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1369,6 +1597,10 @@ static void test_seal_mremap_shrink_fixed(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else
          FAIL_TEST_IF_FALSE(ret2 == newAddr);
  
  

@@ -1383,6 +1615,7 @@ static void test_seal_mremap_expand_fixed(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(page_size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1400,6 +1633,10 @@ static void test_seal_mremap_expand_fixed(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(newAddr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else
          FAIL_TEST_IF_FALSE(ret2 == newAddr);
  
  

@@ -1414,6 +1651,7 @@ static void test_seal_mremap_move_fixed(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1430,6 +1668,10 @@ static void test_seal_mremap_move_fixed(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(newAddr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else
          FAIL_TEST_IF_FALSE(ret2 == newAddr);
  
  

@@ -1443,6 +1685,7 @@ static void test_seal_mremap_move_fixed_zero(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1460,9 +1703,12 @@ static void test_seal_mremap_move_fixed_zero(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

• } else {
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
          FAIL_TEST_IF_FALSE(ret2 == 0);
  

• }
  
  REPORT_TEST_PASS();
  

} @@ -1474,6 +1720,7 @@ static void test_seal_mremap_move_dontunmap(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1488,6 +1735,10 @@ static void test_seal_mremap_move_dontunmap(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else {
          /* kernel will allocate a new address */
          FAIL_TEST_IF_FALSE(ret2 != MAP_FAILED);
  

@@ -1503,6 +1754,7 @@ static void test_seal_mremap_move_dontunmap_anyaddr(bool seal) unsigned long size = 4 * page_size; int ret; void *ret2;

• int prot;
  
  setup_single_address(size, &ptr);
  FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

@@ -1529,6 +1781,10 @@ static void test_seal_mremap_move_dontunmap_anyaddr(bool seal) if (seal) { FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED); FAIL_TEST_IF_FALSE(errno == EPERM);

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  } else {
          /* remap success and return ptr2 */
          FAIL_TEST_IF_FALSE(ret2 ==  ptr2);
  

@@ -1690,9 +1946,10 @@ static void test_seal_discard_ro_anon_on_pkey(bool seal) /* sealing will take effect if PKRU deny write. */ set_pkey(pkey, PKEY_DISABLE_WRITE); ret = sys_madvise(ptr, size, MADV_DONTNEED);

• if (seal)
  

• if (seal) {
          FAIL_TEST_IF_FALSE(ret < 0);
  

• else
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

• } else
          FAIL_TEST_IF_FALSE(!ret);
  
  /* base seal still apply. */
  

FWIW I can't review any of the above. It's still a hard to review patch with a bunch of unrelated changes including VMA size, random errno checks, random vma size checks, etc.

The EPERM is the standard error code for modifying the sealed memory. The vma size and prot is to verify the sealed memory isn't changed after modifying the sealed memory.

Those are all "must-check" parts of verifying the sealing. Now, previously with out-of-loop checks, there is no need to check any of those because once EPERM is returned, nothing will be modified. With in-loop change, this becomes necessary. I do not think it is reasonable to split the case further, i.e. go to the exact same scenario multiple times to check different attributes of sealing.

Thanks -Jeff

Maybe break this down in separate patches.

...

@@ -1876,6 +2133,15 @@ int main(int argc, char **argv) if (!pkey_supported()) ksft_print_msg("PKEY not supported\n");

• /*
  

•  * Possible reasons:
  

•  * - unable to read /proc/pid/maps (unlikely)
  

•  * - parsing error when reading /proc/pid/maps,e.g. len is not expected.
  

•  *   Is this "TOPDOWN" mapping or format change in /proc/pid/maps ?
  

Why do we care? I don't think running selftests without a procfs mount is supported in any way... Format won't change.

-- Pedro

On Thu, Aug 29, 2024 at 09:43:50PM GMT, jeffxu@chromium.org wrote:

From: Jeff Xu jeffxu@chromium.org

Add a testcase to cover all sealed madvise type.

Signed-off-by: Jeff Xu jeffxu@chromium.org

tools/testing/selftests/mm/mseal_test.c | 108 +++++++++++++++++++++++- 1 file changed, 107 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/mseal_test.c b/tools/testing/selftests/mm/mseal_test.c index adc646cf576c..ae06c354220d 100644 --- a/tools/testing/selftests/mm/mseal_test.c +++ b/tools/testing/selftests/mm/mseal_test.c @@ -2121,6 +2121,107 @@ static void test_seal_madvise_nodiscard(bool seal) REPORT_TEST_PASS(); } +static void test_seal_discard_madvise_advice(void) +{

• void *ptr;
• unsigned long page_size = getpagesize();
• unsigned long size = 4 * page_size;
• int ret;
• int sealed_advice[] = {MADV_FREE, MADV_DONTNEED,

• MADV_DONTNEED_LOCKED, MADV_REMOVE,
  

• MADV_DONTFORK, MADV_WIPEONFORK};
  

• int size_sealed_advice = sizeof(sealed_advice) / sizeof(int);
• setup_single_address(size, &ptr);
• FAIL_TEST_IF_FALSE(ptr != (void *)-1);
• ret = seal_single_address(ptr, size);
• FAIL_TEST_IF_FALSE(!ret);
• for (int i = 0; i < size_sealed_advice; i++) {

• ret = sys_madvise(ptr, size, sealed_advice[i]);
  

• FAIL_TEST_IF_FALSE(ret < 0);
  

• FAIL_TEST_IF_FALSE(errno == EPERM);
  

• }
• REPORT_TEST_PASS();

+}

This can replace some of the other 9 discard tests already there, no?

+static void test_munmap_free_multiple_ranges(bool seal) +{

• void *ptr;
• unsigned long page_size = getpagesize();
• unsigned long size = 8 * page_size;
• int ret;
• int prot;
• setup_single_address(size, &ptr);
• FAIL_TEST_IF_FALSE(ptr != (void *)-1);
• /* unmap one page from beginning. */
• ret = sys_munmap(ptr, page_size);
• FAIL_TEST_IF_FALSE(!ret);
• /* unmap one page from middle. */
• ret = sys_munmap(ptr + 4 * page_size, page_size);
• FAIL_TEST_IF_FALSE(!ret);
• size = get_vma_size(ptr + page_size, &prot);
• FAIL_TEST_IF_FALSE(size == 3 * page_size);
• FAIL_TEST_IF_FALSE(prot == 4);
• size = get_vma_size(ptr + 5 * page_size, &prot);
• FAIL_TEST_IF_FALSE(size == 3 * page_size);
• FAIL_TEST_IF_FALSE(prot == 4);
• /* seal the last page */
• if (seal) {

• ret = sys_mseal(ptr + 7 * page_size, page_size);
  

• FAIL_TEST_IF_FALSE(!ret);
  

• size = get_vma_size(ptr +  1 * page_size, &prot);
  

• FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

• FAIL_TEST_IF_FALSE(prot == 4);
  

• size = get_vma_size(ptr +  5 * page_size, &prot);
  

• FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

• FAIL_TEST_IF_FALSE(prot == 4);
  

• size = get_vma_size(ptr +  7 * page_size, &prot);
  

• FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

• FAIL_TEST_IF_FALSE(prot == 4);
  

• }
• /* munmap all 8 pages from beginning */
• ret = sys_munmap(ptr, 8 * page_size);
• if (seal) {

• FAIL_TEST_IF_FALSE(ret);
  

• /* verify mapping are not changed */
  

• size = get_vma_size(ptr + 1 * page_size, &prot);
  

• FAIL_TEST_IF_FALSE(size == 3 * page_size);
  

• FAIL_TEST_IF_FALSE(prot == 4);
  

• size = get_vma_size(ptr +  5 * page_size, &prot);
  

• FAIL_TEST_IF_FALSE(size == 2 * page_size);
  

• FAIL_TEST_IF_FALSE(prot == 4);
  

• size = get_vma_size(ptr +  7 * page_size, &prot);
  

• FAIL_TEST_IF_FALSE(size == 1 * page_size);
  

• FAIL_TEST_IF_FALSE(prot == 4);
  

• } else {

• FAIL_TEST_IF_FALSE(!ret);
  

• for (int i = 0; i < 8; i++) {
  

• 	size = get_vma_size(ptr, &prot);
  

• 	FAIL_TEST_IF_FALSE(size == 0);
  

• }
  

• }
• REPORT_TEST_PASS();

+}

Unrelated munmap change.

Hi Pedro

On Fri, Aug 30, 2024 at 5:57 AM Pedro Falcato pedro.falcato@gmail.com wrote:

On Thu, Aug 29, 2024 at 09:43:51PM GMT, jeffxu@chromium.org wrote:

...

From: Jeff Xu jeffxu@chromium.org

Add sealing test to cover mmap for Expand/shrink across vmas. Reuse the same address in !MAP_FIXED case.

Signed-off-by: Jeff Xu jeffxu@chromium.org

tools/testing/selftests/mm/mseal_test.c | 125 +++++++++++++++++++++++- 1 file changed, 124 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/mseal_test.c b/tools/testing/selftests/mm/mseal_test.c index ae06c354220d..d83538039e76 100644 --- a/tools/testing/selftests/mm/mseal_test.c +++ b/tools/testing/selftests/mm/mseal_test.c @@ -2222,6 +2222,122 @@ static void test_munmap_free_multiple_ranges(bool seal) REPORT_TEST_PASS(); }

+static void test_seal_mmap_expand_seal_middle(bool seal) +{

• void *ptr;
  

• unsigned long page_size = getpagesize();
  

• unsigned long size = 12 * page_size;
  

• int ret;
  

• void *ret2;
  

• int prot;
  

• setup_single_address(size, &ptr);
  

• FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

• /* ummap last 4 pages. */
  

• ret = sys_munmap(ptr + 8 * page_size, 4 * page_size);
  

• FAIL_TEST_IF_FALSE(!ret);
  

• size = get_vma_size(ptr, &prot);
  

• FAIL_TEST_IF_FALSE(size == 8 * page_size);
  

• FAIL_TEST_IF_FALSE(prot == 0x4);
  

• if (seal) {
  

•         ret = sys_mseal(ptr + 4 * page_size, 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(!ret);
  

• }
  

• /* use mmap to expand. */
  

• ret2 = mmap(ptr, 12 * page_size, PROT_READ,
  

•                 MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
  

This is not expansion, but overwriting. Expansion is allowed through an adjacent mmap + mseal (which will merge the two VMAs).

The mmap is trying to expand the address range beginning from ptr (size 8 * page_size) to 12 * page_size. This is overwrite + expansion.

...

• if (seal) {
  

•         FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 4 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
  

•         FAIL_TEST_IF_FALSE(ret2 == ptr);
  

• REPORT_TEST_PASS();
  

+}

+static void test_seal_mmap_shrink_seal_middle(bool seal) +{

• void *ptr;
  

• unsigned long page_size = getpagesize();
  

• unsigned long size = 12 * page_size;
  

• int ret;
  

• void *ret2;
  

• int prot;
  

• setup_single_address(size, &ptr);
  

• FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

• if (seal) {
  

•         ret = sys_mseal(ptr + 4 * page_size, 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(!ret);
  

• }
  

• /* use mmap to shrink. */
  

• ret2 = mmap(ptr, 7 * page_size, PROT_READ,
  

•                 MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
  

This is also a partial overwrite.

The mmap is trying to shrink the address range beginning from ptr (size 12 * page_size) to 8 * page_size. This is overwrite + shrink.

...

• if (seal) {
  

•         FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
  

•         FAIL_TEST_IF_FALSE(errno == EPERM);
  

•         size = get_vma_size(ptr, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 4 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

•         size = get_vma_size(ptr + 4 * page_size, &prot);
  

•         FAIL_TEST_IF_FALSE(size == 4 * page_size);
  

•         FAIL_TEST_IF_FALSE(prot == 0x4);
  

• } else
  

•         FAIL_TEST_IF_FALSE(ret2 == ptr);
  

• REPORT_TEST_PASS();
  

+}

+static void test_seal_mmap_reuse_addr(bool seal) +{

• void *ptr;
  

• unsigned long page_size = getpagesize();
  

• unsigned long size = page_size;
  

• int ret;
  

• void *ret2;
  

• int prot;
  

• setup_single_address(size, &ptr);
  

• FAIL_TEST_IF_FALSE(ptr != (void *)-1);
  

• if (seal) {
  

•         ret = sys_mseal(ptr, size);
  

•         FAIL_TEST_IF_FALSE(!ret);
  

• }
  

• /* use mmap to change protection. */
  

• ret2 = mmap(ptr, size, PROT_NONE,
  

•                 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
  

This is also an overwrite. You're semantically testing the same thing, and testing the same regions of code.

This is not overwriting. MAP_FIXED is not used.

-Jeff

These 3 tests are all kind of the same thing.

-- Pedro