From: "David Hildenbrand (Arm)" <david@kernel.org>
To: longlong yan <yanlonglong@kylinos.cn>,
akpm@linux-foundation.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, shuah@kernel.org
Subject: Re: [PATCH] selftests/mm/pagemap_ioctl: Fix missing NULL checks after calloc()
Date: Tue, 21 Jul 2026 16:55:19 +0200 [thread overview]
Message-ID: <2ea6ee0f-ae22-4961-ba8e-7c4794a692fc@kernel.org> (raw)
In-Reply-To: <20260721063611.342-1-yanlonglong@kylinos.cn>
On 7/21/26 08:36, longlong yan wrote:
> The pagemap_ioctl selftest allocates memory via calloc() in several
> places but does not check the return values. If calloc() fails, the
> subsequent code will dereference a NULL pointer and crash.
>
> Additionally, in sanity_tests(), the calloc() failure check incorrectly
> uses MAP_FAILED (the mmap() error constant) instead of NULL. Since
> calloc() returns NULL on failure, the check never triggers and a
> failed allocation goes undetected.
>
> Add NULL checks after each calloc() call, and fix the wrong error
> constant in sanity_tests(). Use ksft_exit_fail_msg() consistent with
> the existing error handling pattern in the file.
>
> Signed-off-by: longlong yan <yanlonglong@kylinos.cn>
> ---
> tools/testing/selftests/mm/pagemap_ioctl.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
> index f9bcff8e78fa..f6629f44a13d 100644
> --- a/tools/testing/selftests/mm/pagemap_ioctl.c
> +++ b/tools/testing/selftests/mm/pagemap_ioctl.c
> @@ -212,6 +212,8 @@ int userfaultfd_tests(void)
>
> vec_size = mem_size/page_size;
> vec = calloc(vec_size, sizeof(struct page_region));
> + if (!vec)
> + ksft_exit_fail_msg("error nomem\n");
>
> written = pagemap_ioctl(mem, mem_size, vec, 1, PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
> vec_size - 2, PAGE_IS_WRITTEN, 0, 0, PAGE_IS_WRITTEN);
> @@ -699,6 +701,8 @@ int base_tests(char *prefix, char *mem, unsigned long long mem_size, int skip)
> vec_size = mem_size/page_size;
> vec = calloc(vec_size, sizeof(struct page_region));
> vec2 = calloc(vec_size, sizeof(struct page_region));
> + if (!vec || !vec2)
> + ksft_exit_fail_msg("error nomem\n");
>
> /* 1. all new pages must be not be written (dirty) */
> written = pagemap_ioctl(mem, mem_size, vec, 1, PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
> @@ -1000,6 +1004,8 @@ int unmapped_region_tests(void)
> int written, len = 0x00040000;
> long vec_size = len / page_size;
> struct page_region *vec = calloc(vec_size, sizeof(struct page_region));
> + if (!vec)
> + ksft_exit_fail_msg("error nomem\n");
>
> /* 1. Get written pages */
> written = pagemap_ioctl(start, len, vec, vec_size, 0, 0,
> @@ -1116,7 +1122,7 @@ int sanity_tests(void)
>
> vec = calloc(vec_size, sizeof(struct page_region));
> mem = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
> - if (mem == MAP_FAILED || vec == MAP_FAILED)
> + if (mem == MAP_FAILED || !vec)
> ksft_exit_fail_msg("error nomem\n");
>
> wp_init(mem, mem_size);
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
next prev parent reply other threads:[~2026-07-21 14:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-21 6:36 [PATCH] selftests/mm/pagemap_ioctl: Fix missing NULL checks after calloc() longlong yan
2026-07-21 14:55 ` David Hildenbrand (Arm) [this message]
2026-07-22 0:18 ` SJ Park
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