From: Dan Carpenter <dan.carpenter@oracle.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: alsa-devel@alsa-project.org, g@b4.vu, yuehaibing@huawei.com,
andreyknvl@google.com, linux-usb@vger.kernel.org,
syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org,
rfontana@redhat.com, tiwai@suse.com,
syzbot <syzbot+0620f79a1978b1133fd7@syzkaller.appspotmail.com>,
benquike@gmail.com
Subject: Re: [alsa-devel] KASAN: slab-out-of-bounds Read in build_audio_procunit
Date: Mon, 28 Oct 2019 17:34:06 +0300 [thread overview]
Message-ID: <20191028143406.GE1922@kadam> (raw)
In-Reply-To: <s5hsgnkdbsl.wl-tiwai@suse.de>
I wish that this could have been detected with static analysis...
On Tue, Oct 22, 2019 at 05:45:14PM +0200, Takashi Iwai wrote:
> diff --git a/sound/usb/validate.c b/sound/usb/validate.c
> index 3c8f73a0eb12..a5e584b60dcd 100644
> --- a/sound/usb/validate.c
> +++ b/sound/usb/validate.c
> @@ -75,7 +75,7 @@ static bool validate_processing_unit(const void *p,
>
> if (d->bLength < sizeof(*d))
^^^^^^^^^^^^^^^^^^^^^^^
So we know that d->bLength is >= 10.
> return false;
> - len = d->bLength < sizeof(*d) + d->bNrInPins;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Len is 1 or 0.
> + len = sizeof(*d) + d->bNrInPins;
> if (d->bLength < len)
^^^^^^^^^^^^^^^^
So this condition can't be false.
> return false;
But it just makes this return into dead code and we have a lot of dead
code paths in the kernel so it doesn't make sense to generate a warning.
... I don't know if I have a solution.
Maybe some day we will have a vim pluggin which will highlight all the
dead paths and someone would notice that it that way.
regards,
dan carpenter
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WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: syzbot <syzbot+0620f79a1978b1133fd7@syzkaller.appspotmail.com>,
alsa-devel@alsa-project.org, andreyknvl@google.com,
benquike@gmail.com, g@b4.vu, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org, perex@perex.cz, rfontana@redhat.com,
syzkaller-bugs@googlegroups.com, tiwai@suse.com,
yuehaibing@huawei.com
Subject: Re: KASAN: slab-out-of-bounds Read in build_audio_procunit
Date: Mon, 28 Oct 2019 17:34:06 +0300 [thread overview]
Message-ID: <20191028143406.GE1922@kadam> (raw)
In-Reply-To: <s5hsgnkdbsl.wl-tiwai@suse.de>
I wish that this could have been detected with static analysis...
On Tue, Oct 22, 2019 at 05:45:14PM +0200, Takashi Iwai wrote:
> diff --git a/sound/usb/validate.c b/sound/usb/validate.c
> index 3c8f73a0eb12..a5e584b60dcd 100644
> --- a/sound/usb/validate.c
> +++ b/sound/usb/validate.c
> @@ -75,7 +75,7 @@ static bool validate_processing_unit(const void *p,
>
> if (d->bLength < sizeof(*d))
^^^^^^^^^^^^^^^^^^^^^^^
So we know that d->bLength is >= 10.
> return false;
> - len = d->bLength < sizeof(*d) + d->bNrInPins;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Len is 1 or 0.
> + len = sizeof(*d) + d->bNrInPins;
> if (d->bLength < len)
^^^^^^^^^^^^^^^^
So this condition can't be false.
> return false;
But it just makes this return into dead code and we have a lot of dead
code paths in the kernel so it doesn't make sense to generate a warning.
... I don't know if I have a solution.
Maybe some day we will have a vim pluggin which will highlight all the
dead paths and someone would notice that it that way.
regards,
dan carpenter
next prev parent reply other threads:[~2019-10-28 14:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-22 14:54 [alsa-devel] KASAN: slab-out-of-bounds Read in build_audio_procunit syzbot
2019-10-22 14:54 ` syzbot
2019-10-22 15:45 ` [alsa-devel] " Takashi Iwai
2019-10-22 15:45 ` Takashi Iwai
2019-10-28 14:34 ` Dan Carpenter [this message]
2019-10-28 14:34 ` Dan Carpenter
2019-10-28 14:42 ` [alsa-devel] " Takashi Iwai
2019-10-28 14:42 ` Takashi Iwai
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