From: Takashi Iwai <tiwai(a)suse.de>
stable inclusion
from stable-v5.10.44
commit bd7d88b0874f82f7b29d1a53e574cedaf23166ba
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9R4II
CVE: CVE-2021-47281
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id…
--------------------------------
commit 83e197a8414c0ba545e7e3916ce05f836f349273 upstream.
The timer instance per queue is exclusive, and snd_seq_timer_open()
should have managed the concurrent accesses. It looks as if it's
checking the already existing timer instance at the beginning, but
it's not right, because there is no protection, hence any later
concurrent call of snd_seq_timer_open() may override the timer
instance easily. This may result in UAF, as the leftover timer
instance can keep running while the queue itself gets closed, as
spotted by syzkaller recently.
For avoiding the race, add a proper check at the assignment of
tmr->timeri again, and return -EBUSY if it's been already registered.
Reported-by: syzbot+ddc1260a83ed1cbf6fb5(a)syzkaller.appspotmail.com
Cc: <stable(a)vger.kernel.org>
Link: https://lore.kernel.org/r/000000000000dce34f05c42f110c@google.com
Link: https://lore.kernel.org/r/20210610152059.24633-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai(a)suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102(a)huawei.com>
Acked-by: Weilong Chen <chenweilong(a)huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai(a)huawei.com>
Conflicts:
sound/core/seq/seq_timer.c
[Some contexts different. No functional impact.]
Signed-off-by: Zheng Zucheng <zhengzucheng(a)huawei.com>
---
sound/core/seq/seq_timer.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/sound/core/seq/seq_timer.c b/sound/core/seq/seq_timer.c
index f587d0e27476..168256b58313 100644
--- a/sound/core/seq/seq_timer.c
+++ b/sound/core/seq/seq_timer.c
@@ -308,8 +308,15 @@ int snd_seq_timer_open(struct snd_seq_queue *q)
t->callback_data = q;
t->flags |= SNDRV_TIMER_IFLG_AUTO;
spin_lock_irq(&tmr->lock);
- tmr->timeri = t;
+ if (tmr->timeri)
+ err = -EBUSY;
+ else
+ tmr->timeri = t;
spin_unlock_irq(&tmr->lock);
+ if (err < 0) {
+ snd_timer_close(t);
+ return err;
+ }
return 0;
}
--
2.34.1
From: Takashi Iwai <tiwai(a)suse.de>
stable inclusion
from stable-v5.10.44
commit bd7d88b0874f82f7b29d1a53e574cedaf23166ba
category: bugfix
bugzilla: 109295
CVE: CVE-2021-47281
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id…
--------------------------------
commit 83e197a8414c0ba545e7e3916ce05f836f349273 upstream.
The timer instance per queue is exclusive, and snd_seq_timer_open()
should have managed the concurrent accesses. It looks as if it's
checking the already existing timer instance at the beginning, but
it's not right, because there is no protection, hence any later
concurrent call of snd_seq_timer_open() may override the timer
instance easily. This may result in UAF, as the leftover timer
instance can keep running while the queue itself gets closed, as
spotted by syzkaller recently.
For avoiding the race, add a proper check at the assignment of
tmr->timeri again, and return -EBUSY if it's been already registered.
Reported-by: syzbot+ddc1260a83ed1cbf6fb5(a)syzkaller.appspotmail.com
Cc: <stable(a)vger.kernel.org>
Link: https://lore.kernel.org/r/000000000000dce34f05c42f110c@google.com
Link: https://lore.kernel.org/r/20210610152059.24633-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai(a)suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102(a)huawei.com>
Acked-by: Weilong Chen <chenweilong(a)huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai(a)huawei.com>
Signed-off-by: Zheng Zucheng <zhengzucheng(a)huawei.com>
---
sound/core/seq/seq_timer.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/sound/core/seq/seq_timer.c b/sound/core/seq/seq_timer.c
index f587d0e27476..4c9384f1189d 100644
--- a/sound/core/seq/seq_timer.c
+++ b/sound/core/seq/seq_timer.c
@@ -308,8 +308,16 @@ int snd_seq_timer_open(struct snd_seq_queue *q)
t->callback_data = q;
t->flags |= SNDRV_TIMER_IFLG_AUTO;
spin_lock_irq(&tmr->lock);
- tmr->timeri = t;
+ if (tmr->timeri)
+ err = -EBUSY;
+ else
+ tmr->timeri = t;
spin_unlock_irq(&tmr->lock);
+ if (err < 0) {
+ snd_timer_close(t);
+ snd_timer_instance_free(t);
+ return err;
+ }
return 0;
}
--
2.34.1