The "initial_nr_hugepages" variable is unsigned long so it takes up to 20 characters to print, plus 1 more character for the NUL terminator. Unfortunately, this buffer is not quite large enough for the terminator to fit. Also use snprintf() for a belt and suspenders approach.
Fixes: fb9293b6b015 ("selftests/mm: compaction_test: fix bogus test success and reduce probability of OOM-killer invocation") Signed-off-by: Dan Carpenter dan.carpenter@linaro.org --- tools/testing/selftests/mm/compaction_test.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c index e140558e6f53..2c3a0eb6b22d 100644 --- a/tools/testing/selftests/mm/compaction_test.c +++ b/tools/testing/selftests/mm/compaction_test.c @@ -89,9 +89,10 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size, int fd, ret = -1; int compaction_index = 0; char nr_hugepages[20] = {0}; - char init_nr_hugepages[20] = {0}; + char init_nr_hugepages[24] = {0};
- sprintf(init_nr_hugepages, "%lu", initial_nr_hugepages); + snprintf(init_nr_hugepages, sizeof(init_nr_hugepages), + "%lu", initial_nr_hugepages);
/* We want to test with 80% of available memory. Else, OOM killer comes in to play */
On 8/9/24 06:32, Dan Carpenter wrote:
The "initial_nr_hugepages" variable is unsigned long so it takes up to 20 characters to print, plus 1 more character for the NUL terminator. Unfortunately, this buffer is not quite large enough for the terminator to fit. Also use snprintf() for a belt and suspenders approach.
Fixes: fb9293b6b015 ("selftests/mm: compaction_test: fix bogus test success and reduce probability of OOM-killer invocation") Signed-off-by: Dan Carpenter dan.carpenter@linaro.org
tools/testing/selftests/mm/compaction_test.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c index e140558e6f53..2c3a0eb6b22d 100644 --- a/tools/testing/selftests/mm/compaction_test.c +++ b/tools/testing/selftests/mm/compaction_test.c @@ -89,9 +89,10 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size, int fd, ret = -1; int compaction_index = 0; char nr_hugepages[20] = {0};
- char init_nr_hugepages[20] = {0};
- char init_nr_hugepages[24] = {0};
Can we exceed this limit too? Can you make this a define?
- sprintf(init_nr_hugepages, "%lu", initial_nr_hugepages);
- snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
"%lu", initial_nr_hugepages);/* We want to test with 80% of available memory. Else, OOM killer comes in to play */
With that change:
Reviewed-by: Shuah Khan skhan@linuxfoundation.org
thanks, -- Shuah
On Fri, Aug 09, 2024 at 11:20:48AM -0600, Shuah Khan wrote:
On 8/9/24 06:32, Dan Carpenter wrote:
The "initial_nr_hugepages" variable is unsigned long so it takes up to 20 characters to print, plus 1 more character for the NUL terminator. Unfortunately, this buffer is not quite large enough for the terminator to fit. Also use snprintf() for a belt and suspenders approach.
Fixes: fb9293b6b015 ("selftests/mm: compaction_test: fix bogus test success and reduce probability of OOM-killer invocation") Signed-off-by: Dan Carpenter dan.carpenter@linaro.org
tools/testing/selftests/mm/compaction_test.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c index e140558e6f53..2c3a0eb6b22d 100644 --- a/tools/testing/selftests/mm/compaction_test.c +++ b/tools/testing/selftests/mm/compaction_test.c @@ -89,9 +89,10 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size, int fd, ret = -1; int compaction_index = 0; char nr_hugepages[20] = {0};
- char init_nr_hugepages[20] = {0};
- char init_nr_hugepages[24] = {0};
Can we exceed this limit too? Can you make this a define?
It's based on counting the digits in U64_MAX.
18446744073709551615X 123456789012345678901
We don't have any defines for that kind of thing. It's not a bad idea. #define STRLEN_U64_MAX 20 char init_nr_hugepages[STRLEN_U64_MAX + 1];
But it should be done as part of a kernel wide clean up and not part of this buffer overflow fix. The line above it could be changed as well, for example. Let me create a KTODO and hope the internet will take care of it.
KTODO: create defines for STRLEN_[SU]8/16/32/64_MIN/MAX.
Btw, I rounded up to 24 just because I like buffer sizes that are divisible by 4 but the compiler is probably going to do that automatically either way.
regards, dan carpenter
linux-kselftest-mirror@lists.linaro.org
-
Dan Carpenter -
Shuah Khan