From: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx> commit 2f7a26abb8241a0208c68d22815aa247c5ddacab upstream. 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@xxxxxxxxxx/ Reported-and-tested-by: syzbot+205eb15961852c2c5974@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220409012655.9399-1-fmdefrancesco@xxxxxxxxx Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- sound/core/pcm_misc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/sound/core/pcm_misc.c +++ b/sound/core/pcm_misc.c @@ -406,7 +406,7 @@ int snd_pcm_format_set_silence(snd_pcm_f 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) {
