linux-kernel - [PATCH 5.4 28/34] ALSA: pcm: oss: Fix potential out-of-bounds shift

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20201219125342.779367828@linuxfoundation.org>
Date:   Sat, 19 Dec 2020 14:03:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+df7dc146ebdd6435eea3@...kaller.appspotmail.com,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 5.4 28/34] ALSA: pcm: oss: Fix potential out-of-bounds shift

From: Takashi Iwai <tiwai@...e.de>

commit 175b8d89fe292796811fdee87fa39799a5b6b87a upstream.

syzbot spotted a potential out-of-bounds shift in the PCM OSS layer
where it calculates the buffer size with the arbitrary shift value
given via an ioctl.

Add a range check for avoiding the undefined behavior.
As the value can be treated by a signed integer, the max shift should
be 30.

Reported-by: syzbot+df7dc146ebdd6435eea3@...kaller.appspotmail.com
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20201209084552.17109-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/core/oss/pcm_oss.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -1934,11 +1934,15 @@ static int snd_pcm_oss_set_subdivide(str
 static int snd_pcm_oss_set_fragment1(struct snd_pcm_substream *substream, unsigned int val)
 {
 	struct snd_pcm_runtime *runtime;
+	int fragshift;
 
 	runtime = substream->runtime;
 	if (runtime->oss.subdivision || runtime->oss.fragshift)
 		return -EINVAL;
-	runtime->oss.fragshift = val & 0xffff;
+	fragshift = val & 0xffff;
+	if (fragshift >= 31)
+		return -EINVAL;
+	runtime->oss.fragshift = fragshift;
 	runtime->oss.maxfrags = (val >> 16) & 0xffff;
 	if (runtime->oss.fragshift < 4)		/* < 16 */
 		runtime->oss.fragshift = 4;