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Date: Wed, 23 Nov 2022 15:06:16 +0800 From: butt3rflyh4ck <butterflyhuangxx@...il.com> To: Takashi Iwai <tiwai@...e.de> Cc: perex@...ex.cz, tiwai@...e.com, baolin.wang@...ux.alibaba.com, alsa-devel@...a-project.org, linux-kernel@...r.kernel.org Subject: Re: [RESEND PATCH] ALSA: rawmidi: fix infoleak in snd_rawmidi_ioctl_status_compat64 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@...e.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@...il.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
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