Re: [PATCH] [v2] ALSA: core: fix buffer overflow in test_format_fill_silence()

[Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>]

On Sat, 17 Feb 2024 at 16:13, Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> KASAN caught a buffer overflow with the hardcoded 2048 byte buffer
> size, when 2080 bytes are written to it:
>
>  BUG: KASAN: slab-out-of-bounds in snd_pcm_format_set_silence+0x3bc/0x3e4
>  Write of size 8 at addr ffff0000c8149800 by task kunit_try_catch/1297
>
>  CPU: 0 PID: 1297 Comm: kunit_try_catch Tainted: G N 6.8.0-rc4-next-20240216 #1
>  Hardware name: linux,dummy-virt (DT)
>  Call trace:
>   kasan_report+0x78/0xc0
>   __asan_report_store_n_noabort+0x1c/0x28
>   snd_pcm_format_set_silence+0x3bc/0x3e4
>   _test_fill_silence+0xdc/0x298
>   test_format_fill_silence+0x110/0x228
>   kunit_try_run_case+0x144/0x3bc
>   kunit_generic_run_threadfn_adapter+0x50/0x94
>   kthread+0x330/0x3e8
>   ret_from_fork+0x10/0x20
>
>  Allocated by task 1297:
>   __kmalloc+0x17c/0x2f0
>   kunit_kmalloc_array+0x2c/0x78
>   test_format_fill_silence+0xcc/0x228
>   kunit_try_run_case+0x144/0x3bc
>   kunit_generic_run_threadfn_adapter+0x50/0x94
>   kthread+0x330/0x3e8
>   ret_from_fork+0x10/0x20
>
> Replace the incorrect size with the correct length of 260 64-bit samples.
>
> Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
> Suggested-by: Ivan Orlov <ivan.orlov0322@xxxxxxxxx>
> Fixes: 3e39acf56ede ("ALSA: core: Add sound core KUnit test")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

> ---
> v2: use a named constant as suggested by Ivan Orlov
> ---
>  sound/core/sound_kunit.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/sound/core/sound_kunit.c b/sound/core/sound_kunit.c
> index 5d5a7bf88de4..4212c4a20697 100644
> --- a/sound/core/sound_kunit.c
> +++ b/sound/core/sound_kunit.c
> @@ -8,7 +8,8 @@
>  #include <sound/core.h>
>  #include <sound/pcm.h>
>
> -#define SILENCE_BUFFER_SIZE 2048
> +#define SILENCE_BUFFER_MAX_FRAMES 260
> +#define SILENCE_BUFFER_SIZE (sizeof(u64) * SILENCE_BUFFER_MAX_FRAMES)
>  #define SILENCE(...) { __VA_ARGS__ }
>  #define DEFINE_FORMAT(fmt, pbits, wd, endianness, signd, silence_arr) {                \
>         .format = SNDRV_PCM_FORMAT_##fmt, .physical_bits = pbits,               \
> @@ -165,7 +166,7 @@ static void _test_fill_silence(struct kunit *test, struct snd_format_test_data *
>
>  static void test_format_fill_silence(struct kunit *test)
>  {
> -       u32 buf_samples[] = { 10, 20, 32, 64, 129, 260 };
> +       u32 buf_samples[] = { 10, 20, 32, 64, 129, SILENCE_BUFFER_MAX_FRAMES };
>         u8 *buffer;
>         u32 i, j;
>
> --
> 2.39.2
>


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