On 13/08/2019 17:26, Dave Martin wrote:
On Fri, Aug 02, 2019 at 06:02:59PM +0100, Cristian Marussi wrote:
Added a simple fake_sigreturn testcase which builds a ucontext_t
Add
Ok
with a badly sized header that causes a overrun in the __reserved area and place it onto the stack. Expects a SIGSEGV on test PASS.
Signed-off-by: Cristian Marussi cristian.marussi@arm.com
.../arm64/signal/testcases/.gitignore | 1 + .../testcases/fake_sigreturn_bad_size.c | 85 +++++++++++++++++++ 2 files changed, 86 insertions(+) create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c
diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore index 94f9baaf638c..3408e0f5ba98 100644 --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore @@ -8,3 +8,4 @@ fake_sigreturn_bad_magic fake_sigreturn_bad_size_for_magic0 fake_sigreturn_missing_fpsimd fake_sigreturn_duplicated_fpsimd +fake_sigreturn_bad_size diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c new file mode 100644 index 000000000000..1467fb534d8b --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */
signal.h?
Ok
+#include <stdio.h> +#include <ucontext.h>
+#include "test_signals_utils.h" +#include "testcases.h"
+struct fake_sigframe sf;
+#define MIN_SZ_ALIGN 16
+static int fake_sigreturn_bad_size_run(struct tdescr *td,
siginfo_t *si, ucontext_t *uc)+{
- size_t resv_sz, need_sz, offset;
- struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head;
- /* just to fill the ucontext_t with something real */
- if (!get_current_context(td, &sf.uc))
return 1;- resv_sz = GET_SF_RESV_SIZE(sf);
- /*
* find the terminator, preserving existing headers* and verify amount of spare room in __reserved area.*/- head = get_terminator(shead, resv_sz, &offset);
- /*
* try stripping extra_context header when low on space:* we need at least for the bad sized esr_context.double space
ok.
*/- need_sz = HDR_SZ + sizeof(struct esr_context);
- if (head && resv_sz - offset < need_sz) {
fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n",resv_sz - offset);head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset);- }
- /* just give up and timeout if still not enough space */
- if (head && resv_sz - offset >= need_sz) {
fprintf(stderr, "Mangling template header. Spare space:%zd\n",resv_sz - offset);/** Use an esr_context to build a fake header with a* size greater then the free __reserved area minus HDR_SZ;* using ESR_MAGIC here since it is not checked for size nor* is limited to one instance.** At first inject an additional normal esr_context*/head->magic = ESR_MAGIC;head->size = sizeof(struct esr_context);/* and terminate properly */write_terminator_record(GET_RESV_NEXT_HEAD(head));ASSERT_GOOD_CONTEXT(&sf.uc);/** now mess with fake esr_context size: leaving less space than* neededwhile keeping size value 16-aligned** It must trigger a SEGV from Kernel on:** resv_sz - offset < sizeof(*head)*//* at first set the maximum good 16-aligned size */head->size = (resv_sz - offset - need_sz + MIN_SZ_ALIGN) & ~0xfUL;/* plus a bit more of 16-aligned sized stuff */head->size += MIN_SZ_ALIGN;/* and terminate properly */write_terminator_record(GET_RESV_NEXT_HEAD(head));ASSERT_BAD_CONTEXT(&sf.uc);fake_sigreturn(&sf, sizeof(sf), 16);- }
- return 1;
+}
I'll convert to use new helper get_starting_head() to make space in __reserved.
[...]
Otherwise looks reasonable.
Cheers ---Dave
Cheers
Cristian