Syzbot reports "KASAN: null-ptr-deref Write in snd_pcm_format_set_silence".[1]
It is due to missing validation of the "silence" field of struct "pcm_format_data" in "pcm_formats" array.
Add a test for valid "pat" and, if it is not so, return -EINVAL.
[1] https://lore.kernel.org/lkml/000000000000d188ef05dc2c7279@google.com/
Reported-and-tested-by: syzbot+205eb15961852c2c5974@syzkaller.appspotmail.com Signed-off-by: Fabio M. De Francesco fmdefrancesco@gmail.com ---
I wasn't able to figure out the commit for the "Fixes:" tag. If this patch is good, can someone please help with providing this missing information?
sound/core/pcm_misc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/core/pcm_misc.c b/sound/core/pcm_misc.c index 4866aed97aac..5588b6a1ee8b 100644 --- a/sound/core/pcm_misc.c +++ b/sound/core/pcm_misc.c @@ -433,7 +433,7 @@ int snd_pcm_format_set_silence(snd_pcm_format_t format, void *data, unsigned int return 0; width = pcm_formats[(INT)format].phys; /* physical width */ pat = pcm_formats[(INT)format].silence; - if (! width) + if (!width || !pat) return -EINVAL; /* signed or 1 byte data */ if (pcm_formats[(INT)format].signd == 1 || width <= 8) {