Re: [PATCH -next] ALSA: pcm: fix undefined behavior in bit shift for SNDRV_PCM_RATE_KNOT

[zhongbaisong]

在 2022/11/21 18:35, Takashi Iwai 写道:
> On Mon, 21 Nov 2022 03:33:29 +0100,
> Baisong Zhong wrote:
> > Shifting signed 32-bit value by 31 bits is undefined, so changing
> > significant bit to unsigned. The UBSAN warning calltrace like below:
> >
> > UBSAN: shift-out-of-bounds in sound/core/pcm_native.c:2676:21
> > left shift of 1 by 31 places cannot be represented in type 'int'
> > ...
> > Call Trace:
> >   <TASK>
> >   dump_stack_lvl+0x8d/0xcf
> >   ubsan_epilogue+0xa/0x44
> >   __ubsan_handle_shift_out_of_bounds+0x1e7/0x208
> >   snd_pcm_open_substream+0x9f0/0xa90
> >   snd_pcm_oss_open.part.26+0x313/0x670
> >   snd_pcm_oss_open+0x30/0x40
> >   soundcore_open+0x18b/0x2e0
> >   chrdev_open+0xe2/0x270
> >   do_dentry_open+0x2f7/0x620
> >   path_openat+0xd66/0xe70
> >   do_filp_open+0xe3/0x170
> >   do_sys_openat2+0x357/0x4a0
> >   do_sys_open+0x87/0xd0
> >   do_syscall_64+0x34/0x80
> >
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Signed-off-by: Baisong Zhong <zhongbaisong@xxxxxxxxxx>
> > ---
> >   include/sound/pcm.h | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/sound/pcm.h b/include/sound/pcm.h
> > index 7b1a022910e8..ec28c2ec89de 100644
> > --- a/include/sound/pcm.h
> > +++ b/include/sound/pcm.h
> > @@ -123,7 +123,7 @@ struct snd_pcm_ops {
> >   #define SNDRV_PCM_RATE_384000		(1<<14)		/* 384000Hz */
> >   
> >   #define SNDRV_PCM_RATE_CONTINUOUS	(1<<30)		/* continuous range */
> > -#define SNDRV_PCM_RATE_KNOT		(1<<31)		/* supports more non-continuos rates */
> > +#define SNDRV_PCM_RATE_KNOT		(1U<<31)	/* supports more non-continuos rates */
>
> Could you rather update all SNDRV_PCM_RATE_* to 1U?
> Otherwise it'll look inconsistent.
>
>
> thanks,
>
> Takashi

Hi, Takashi
Thank you for your suggestion. I will update all
SNDRV_PCM_RATE_* to 1U for consistency in v2.

Baisong Zhong
.