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authorTakashi Iwai <tiwai@suse.de>2018-06-25 11:09:11 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-03 11:25:04 +0200
commit69f96e9b570a7e09e8493a50068d08174ce3a3a2 (patch)
treee019df3becba6bf45d28590d80f14819ab943ee3
parent3d1de95138fbf54bab0049ae669299e3f1a4c4fe (diff)
downloadlinux-linaro-stable-69f96e9b570a7e09e8493a50068d08174ce3a3a2.tar.gz
ALSA: timer: Fix UBSAN warning at SNDRV_TIMER_IOCTL_NEXT_DEVICE ioctl
commit b41f794f284966fd6ec634111e3b40d241389f96 upstream. The kernel may spew a WARNING about UBSAN undefined behavior at handling ALSA timer ioctl SNDRV_TIMER_IOCTL_NEXT_DEVICE: UBSAN: Undefined behaviour in sound/core/timer.c:1524:19 signed integer overflow: 2147483647 + 1 cannot be represented in type 'int' Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x122/0x1c8 lib/dump_stack.c:113 ubsan_epilogue+0x12/0x86 lib/ubsan.c:159 handle_overflow+0x1c2/0x21f lib/ubsan.c:190 __ubsan_handle_add_overflow+0x2a/0x31 lib/ubsan.c:198 snd_timer_user_next_device sound/core/timer.c:1524 [inline] __snd_timer_user_ioctl+0x204d/0x2520 sound/core/timer.c:1939 snd_timer_user_ioctl+0x67/0x95 sound/core/timer.c:1994 .... It happens only when a value with INT_MAX is passed, as we're incrementing it unconditionally. So the fix is trivial, check the value with INT_MAX. Although the bug itself is fairly harmless, it's better to fix it so that fuzzers won't hit this again later. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200213 Reported-and-tested-by: Team OWL337 <icytxw@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--sound/core/timer.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c
index 4fdc9e11e832..2c0f292226d7 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -1514,7 +1514,7 @@ static int snd_timer_user_next_device(struct snd_timer_id __user *_tid)
} else {
if (id.subdevice < 0)
id.subdevice = 0;
- else
+ else if (id.subdevice < INT_MAX)
id.subdevice++;
}
}