[PATCH] selftests/mm/ksm_functional: prevent unmapping undefined address

[PATCH] selftests/mm/ksm_functional: prevent unmapping undefined address

[JP Kobryn]

Replace some goto statements with return statements so that unmap() is
not called on an undefined address. This change is made so that unmap()
can only be reached after mmap() is called (and the address mentioned is
defined). Returning MAP_FAILED seems acceptable since client code checks
for this value.

Fixes: 42096aa24b82 ("selftest/mm: ksm_functional_tests: test in mmap_and_merge_range() if anything got merged")
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
---
 tools/testing/selftests/mm/ksm_functional_tests.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index fbff0dd09191..d615767e396b 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -155,12 +155,12 @@ static char *mmap_and_merge_range(char val, unsigned long size, int prot,
 	/* Stabilize accounting by disabling KSM completely. */
 	if (ksm_unmerge()) {
 		ksft_test_result_fail("Disabling (unmerging) KSM failed\n");
-		goto unmap;
+		return MAP_FAILED;
 	}
 
 	if (get_my_merging_pages() > 0) {
 		ksft_test_result_fail("Still pages merged\n");
-		goto unmap;
+		return MAP_FAILED;
 	}
 
 	map = mmap(NULL, size, PROT_READ|PROT_WRITE,
-- 
2.43.0

Re: [PATCH] selftests/mm/ksm_functional: prevent unmapping undefined address

[David Hildenbrand]

On 05.01.24 21:24, JP Kobryn wrote:
> Replace some goto statements with return statements so that unmap() is
> not called on an undefined address. This change is made so that unmap()
> can only be reached after mmap() is called (and the address mentioned is
> defined). Returning MAP_FAILED seems acceptable since client code checks
> for this value.
> 
> Fixes: 42096aa24b82 ("selftest/mm: ksm_functional_tests: test in mmap_and_merge_range() if anything got merged")
> Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
> ---
>   tools/testing/selftests/mm/ksm_functional_tests.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
> index fbff0dd09191..d615767e396b 100644
> --- a/tools/testing/selftests/mm/ksm_functional_tests.c
> +++ b/tools/testing/selftests/mm/ksm_functional_tests.c
> @@ -155,12 +155,12 @@ static char *mmap_and_merge_range(char val, unsigned long size, int prot,
>   	/* Stabilize accounting by disabling KSM completely. */
>   	if (ksm_unmerge()) {
>   		ksft_test_result_fail("Disabling (unmerging) KSM failed\n");
> -		goto unmap;
> +		return MAP_FAILED;
>   	}
>   
>   	if (get_my_merging_pages() > 0) {
>   		ksft_test_result_fail("Still pages merged\n");
> -		goto unmap;
> +		return MAP_FAILED;
>   	}
>   
>   	map = mmap(NULL, size, PROT_READ|PROT_WRITE,

Indeed, thanks.

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb