* [PATCH] ALSA: lola: Bounds check loop iterator against streams array size
@ 2022-05-20 16:55 Kees Cook
2022-05-21 6:49 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2022-05-20 16:55 UTC (permalink / raw)
To: Jaroslav Kysela
Cc: Kees Cook, Takashi Iwai, alsa-devel, linux-kernel, linux-hardening
GCC 12 sees that it's technically possible for num_streams to be larger
than ARRAY_SIZE(pcm->streams). Bounds-check the iterator.
../sound/pci/lola/lola_pcm.c: In function 'lola_pcm_update':
../sound/pci/lola/lola_pcm.c:567:64: warning: array subscript [0, 31] is outside array bounds of 'struct lola_stream[16]' [-Warray-bounds]
567 | struct lola_stream *str = &pcm->streams[i];
| ~~~~~~~~~~~~^~~
In file included from ../sound/pci/lola/lola_pcm.c:15:
../sound/pci/lola/lola.h:307:28: note: while referencing 'streams'
307 | struct lola_stream streams[MAX_STREAM_COUNT];
| ^~~~~~~
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: alsa-devel@alsa-project.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
sound/pci/lola/lola_pcm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sound/pci/lola/lola_pcm.c b/sound/pci/lola/lola_pcm.c
index 738ec987000a..32193fae978d 100644
--- a/sound/pci/lola/lola_pcm.c
+++ b/sound/pci/lola/lola_pcm.c
@@ -561,8 +561,9 @@ static snd_pcm_uframes_t lola_pcm_pointer(struct snd_pcm_substream *substream)
void lola_pcm_update(struct lola *chip, struct lola_pcm *pcm, unsigned int bits)
{
int i;
+ u8 num_streams = min_t(u8, pcm->num_streams, ARRAY_SIZE(pcm->streams));
- for (i = 0; bits && i < pcm->num_streams; i++) {
+ for (i = 0; bits && i < num_streams; i++) {
if (bits & (1 << i)) {
struct lola_stream *str = &pcm->streams[i];
if (str->substream && str->running)
--
2.32.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ALSA: lola: Bounds check loop iterator against streams array size
2022-05-20 16:55 [PATCH] ALSA: lola: Bounds check loop iterator against streams array size Kees Cook
@ 2022-05-21 6:49 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2022-05-21 6:49 UTC (permalink / raw)
To: Kees Cook
Cc: Jaroslav Kysela, Takashi Iwai, alsa-devel, linux-kernel, linux-hardening
On Fri, 20 May 2022 18:55:37 +0200,
Kees Cook wrote:
>
> GCC 12 sees that it's technically possible for num_streams to be larger
> than ARRAY_SIZE(pcm->streams). Bounds-check the iterator.
>
> ../sound/pci/lola/lola_pcm.c: In function 'lola_pcm_update':
> ../sound/pci/lola/lola_pcm.c:567:64: warning: array subscript [0, 31] is outside array bounds of 'struct lola_stream[16]' [-Warray-bounds]
> 567 | struct lola_stream *str = &pcm->streams[i];
> | ~~~~~~~~~~~~^~~
> In file included from ../sound/pci/lola/lola_pcm.c:15:
> ../sound/pci/lola/lola.h:307:28: note: while referencing 'streams'
> 307 | struct lola_stream streams[MAX_STREAM_COUNT];
> | ^~~~~~~
>
> Cc: Jaroslav Kysela <perex@perex.cz>
> Cc: Takashi Iwai <tiwai@suse.com>
> Cc: alsa-devel@alsa-project.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
Thanks, applied now.
Takashi
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