| Message ID | 20221123050911.1045190-1-butterflyhuangxx@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RESEND] ALSA: rawmidi: fix infoleak in snd_rawmidi_ioctl_status_compat64 | expand |
On Wed, 23 Nov 2022 06:09:11 +0100, Xiaolong Huang wrote: > > The compat_status is declared off of the stack, so it needs to > be zeroed out before copied back to userspace to prevent any > unintentional data leakage. > > Fixes: d9e5582c4bb2 ("ALSA: Avoid using timespec for struct snd_rawmidi_status") > Signed-off-by: Xiaolong Huang <butterflyhuangxx@gmail.com> > > --- > > Reason for resend: > 1. add Fixes line. > --- > sound/core/rawmidi_compat.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/sound/core/rawmidi_compat.c b/sound/core/rawmidi_compat.c > index 68a93443583c..6afa68165b17 100644 > --- a/sound/core/rawmidi_compat.c > +++ b/sound/core/rawmidi_compat.c > @@ -80,6 +80,7 @@ static int snd_rawmidi_ioctl_status_compat64(struct snd_rawmidi_file *rfile, > if (err < 0) > return err; > > + memset(&compat_status, 0, sizeof(compat_status)); > compat_status = (struct compat_snd_rawmidi_status64) { > .stream = status.stream, > .tstamp_sec = status.tstamp_sec, Here at the line just after your addition, compat_status is fully initialized by substitution, so I believe the memset is superfluous. Or have you verified that it really leaks the uninitialized memory? thanks, Takashi
Hi, the compat_status structure is struct compat_snd_rawmidi_status64 {
s32 stream;
u8 rsvd[4]; /* alignment */
s64 tstamp_sec;
s64 tstamp_nsec;
u32 avail;
u32 xruns;
unsigned char reserved[16];
} __attribute__((packed));
The rsvd[4] and reserved[16] are not initialized.
Regards,
butt3rflyh4ck.
On Wed, Nov 23, 2022 at 2:55 PM Takashi Iwai <tiwai@suse.de> wrote:
>
> On Wed, 23 Nov 2022 06:09:11 +0100,
> Xiaolong Huang wrote:
> >
> > The compat_status is declared off of the stack, so it needs to
> > be zeroed out before copied back to userspace to prevent any
> > unintentional data leakage.
> >
> > Fixes: d9e5582c4bb2 ("ALSA: Avoid using timespec for struct snd_rawmidi_status")
> > Signed-off-by: Xiaolong Huang <butterflyhuangxx@gmail.com>
> >
> > ---
> >
> > Reason for resend:
> > 1. add Fixes line.
> > ---
> > sound/core/rawmidi_compat.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/sound/core/rawmidi_compat.c b/sound/core/rawmidi_compat.c
> > index 68a93443583c..6afa68165b17 100644
> > --- a/sound/core/rawmidi_compat.c
> > +++ b/sound/core/rawmidi_compat.c
> > @@ -80,6 +80,7 @@ static int snd_rawmidi_ioctl_status_compat64(struct snd_rawmidi_file *rfile,
> > if (err < 0)
> > return err;
> >
> > + memset(&compat_status, 0, sizeof(compat_status));
> > compat_status = (struct compat_snd_rawmidi_status64) {
> > .stream = status.stream,
> > .tstamp_sec = status.tstamp_sec,
>
> Here at the line just after your addition, compat_status is fully
> initialized by substitution, so I believe the memset is superfluous.
>
> Or have you verified that it really leaks the uninitialized memory?
>
>
> thanks,
>
> Takashi
On Wed, 23 Nov 2022 08:06:16 +0100, butt3rflyh4ck wrote: > > Hi, the compat_status structure is struct compat_snd_rawmidi_status64 { > s32 stream; > u8 rsvd[4]; /* alignment */ > s64 tstamp_sec; > s64 tstamp_nsec; > u32 avail; > u32 xruns; > unsigned char reserved[16]; > } __attribute__((packed)); > The rsvd[4] and reserved[16] are not initialized. Other members are initialized with zero. https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html Takashi > > > Regards, > butt3rflyh4ck. > > On Wed, Nov 23, 2022 at 2:55 PM Takashi Iwai <tiwai@suse.de> wrote: > > > > On Wed, 23 Nov 2022 06:09:11 +0100, > > Xiaolong Huang wrote: > > > > > > The compat_status is declared off of the stack, so it needs to > > > be zeroed out before copied back to userspace to prevent any > > > unintentional data leakage. > > > > > > Fixes: d9e5582c4bb2 ("ALSA: Avoid using timespec for struct snd_rawmidi_status") > > > Signed-off-by: Xiaolong Huang <butterflyhuangxx@gmail.com> > > > > > > --- > > > > > > Reason for resend: > > > 1. add Fixes line. > > > --- > > > sound/core/rawmidi_compat.c | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/sound/core/rawmidi_compat.c b/sound/core/rawmidi_compat.c > > > index 68a93443583c..6afa68165b17 100644 > > > --- a/sound/core/rawmidi_compat.c > > > +++ b/sound/core/rawmidi_compat.c > > > @@ -80,6 +80,7 @@ static int snd_rawmidi_ioctl_status_compat64(struct snd_rawmidi_file *rfile, > > > if (err < 0) > > > return err; > > > > > > + memset(&compat_status, 0, sizeof(compat_status)); > > > compat_status = (struct compat_snd_rawmidi_status64) { > > > .stream = status.stream, > > > .tstamp_sec = status.tstamp_sec, > > > > Here at the line just after your addition, compat_status is fully > > initialized by substitution, so I believe the memset is superfluous. > > > > Or have you verified that it really leaks the uninitialized memory? > > > > > > thanks, > > > > Takashi > > > > -- > Active Defense Lab of Venustech >
diff --git a/sound/core/rawmidi_compat.c b/sound/core/rawmidi_compat.c index 68a93443583c..6afa68165b17 100644 --- a/sound/core/rawmidi_compat.c +++ b/sound/core/rawmidi_compat.c @@ -80,6 +80,7 @@ static int snd_rawmidi_ioctl_status_compat64(struct snd_rawmidi_file *rfile, if (err < 0) return err; + memset(&compat_status, 0, sizeof(compat_status)); compat_status = (struct compat_snd_rawmidi_status64) { .stream = status.stream, .tstamp_sec = status.tstamp_sec,
The compat_status is declared off of the stack, so it needs to be zeroed out before copied back to userspace to prevent any unintentional data leakage. Fixes: d9e5582c4bb2 ("ALSA: Avoid using timespec for struct snd_rawmidi_status") Signed-off-by: Xiaolong Huang <butterflyhuangxx@gmail.com> --- Reason for resend: 1. add Fixes line. --- sound/core/rawmidi_compat.c | 1 + 1 file changed, 1 insertion(+) base-commit: eb7081409f94a9a8608593d0fb63a1aa3d6f95d8