Re: [PATCH 3.2 57/79] ALSA: usb-audio: Fix potential zero-division at parsing FU

2018-02-13 Thread Ben Hutchings
On Mon, 2018-02-12 at 07:59 +0100, Takashi Iwai wrote:
> On Sun, 11 Feb 2018 05:20:06 +0100,
> Ben Hutchings wrote:
> > 
> > 3.2.99-rc1 review patch.  If anyone has any objections, please let me know.
> > 
> > --
> > 
> > From: Takashi Iwai 
> > 
> > commit 8428a8ebde2db1e988e41a58497a28beb7ce1705 upstream.
> 
> Please drop this.  This patch is broken, and was reverted in the later
> commit 3c02a6d94665.

Thanks, I've dropped this from 3.2 and 3.16 patch queues.

Ben.

> thanks,
> 
> Takashi
> 
> 
> > 
> > parse_audio_feature_unit() contains a code dividing potentially with
> > zero when a malformed FU descriptor is passed.  Although there is
> > already a sanity check, it checks only the value zero, hence it can
> > still lead to a zero-division when a value 1 is passed there.
> > 
> > Fix it by correcting the sanity check (and the error message
> > thereof).
> > 
> > Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0")
> > Signed-off-by: Takashi Iwai 
> > [bwh: Backported to 3.2: adjust context]
> > Signed-off-by: Ben Hutchings 
> > ---
> >  sound/usb/mixer.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > --- a/sound/usb/mixer.c
> > +++ b/sound/usb/mixer.c
> > @@ -1262,9 +1262,9 @@ static int parse_audio_feature_unit(stru
> > return -EINVAL;
> > }
> > csize = hdr->bControlSize;
> > -   if (!csize) {
> > +   if (csize <= 1) {
> > snd_printdd(KERN_ERR "usbaudio: unit %u: "
> > -   "invalid bControlSize == 0\n", unitid);
> > +   "invalid bControlSize <= 1\n", unitid);
> > return -EINVAL;
> > }
> > channels = (hdr->bLength - 7) / csize - 1;
> > 
-- 
Ben Hutchings
friends: People who know you well, but like you anyway.



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Re: [PATCH 3.2 57/79] ALSA: usb-audio: Fix potential zero-division at parsing FU

2018-02-11 Thread Takashi Iwai
On Sun, 11 Feb 2018 05:20:06 +0100,
Ben Hutchings wrote:
> 
> 3.2.99-rc1 review patch.  If anyone has any objections, please let me know.
> 
> --
> 
> From: Takashi Iwai 
> 
> commit 8428a8ebde2db1e988e41a58497a28beb7ce1705 upstream.

Please drop this.  This patch is broken, and was reverted in the later
commit 3c02a6d94665.


thanks,

Takashi


> 
> parse_audio_feature_unit() contains a code dividing potentially with
> zero when a malformed FU descriptor is passed.  Although there is
> already a sanity check, it checks only the value zero, hence it can
> still lead to a zero-division when a value 1 is passed there.
> 
> Fix it by correcting the sanity check (and the error message
> thereof).
> 
> Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0")
> Signed-off-by: Takashi Iwai 
> [bwh: Backported to 3.2: adjust context]
> Signed-off-by: Ben Hutchings 
> ---
>  sound/usb/mixer.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -1262,9 +1262,9 @@ static int parse_audio_feature_unit(stru
>   return -EINVAL;
>   }
>   csize = hdr->bControlSize;
> - if (!csize) {
> + if (csize <= 1) {
>   snd_printdd(KERN_ERR "usbaudio: unit %u: "
> - "invalid bControlSize == 0\n", unitid);
> + "invalid bControlSize <= 1\n", unitid);
>   return -EINVAL;
>   }
>   channels = (hdr->bLength - 7) / csize - 1;
>