[ 30/75] ALSA: seq: Fix missing error handling in snd_seq_timer_open()

Greg Kroah-Hartman
2013-03-18T21:57:43Z

From: Takashi Iwai <tiwai@suse.de>

commit 66efdc71d95887b652a742a5dae51fa834d71465 upstream.

snd_seq_timer_open() didn't catch the whole error path but let through
if the timer id is a slave. This may lead to Oops by accessing the
uninitialized pointer.

BUG: unable to handle kernel NULL pointer dereference at 00000000000002ae
IP: [<ffffffff819b3477>] snd_seq_timer_open+0xe7/0x130
PGD 785cd067 PUD 76964067 PMD 0
Oops: 0002 [#4] SMP
CPU 0
Pid: 4288, comm: trinity-child7 Tainted: G D W 3.9.0-rc1+ #100 Bochs Bochs
RIP: 0010:[<ffffffff819b3477>] [<ffffffff819b3477>] snd_seq_timer_open+0xe7/0x130
RSP: 0018:ffff88006ece7d38 EFLAGS: 00010246
RAX: 0000000000000286 RBX: ffff88007851b400 RCX: 0000000000000000
RDX: 000000000000ffff RSI: ffff88006ece7d58 RDI: ffff88006ece7d38
RBP: ffff88006ece7d98 R08: 000000000000000a R09: 000000000000fffe
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8800792c5400 R14: 0000000000e8f000 R15: 0000000000000007
FS: 00007f7aaa650700(0000) GS:ffff88007f800000(0000) GS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000002ae CR3: 000000006efec000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process trinity-child7 (pid: 4288, threadinfo ffff88006ece6000, task ffff880076a8a290)
Stack:
0000000000000286 ffffffff828f2be0 ffff88006ece7d58 ffffffff810f354d
65636e6575716573 2065756575712072 ffff8800792c0030 0000000000000000
ffff88006ece7d98 ffff8800792c5400 ffff88007851b400 ffff8800792c5520
Call Trace:
[<ffffffff810f354d>] ? trace_hardirqs_on+0xd/0x10
[<ffffffff819b17e9>] snd_seq_queue_timer_open+0x29/0x70
[<ffffffff819ae01a>] snd_seq_ioctl_set_queue_timer+0xda/0x120
[<ffffffff819acb9b>] snd_seq_do_ioctl+0x9b/0xd0
[<ffffffff819acbe0>] snd_seq_ioctl+0x10/0x20
[<ffffffff811b9542>] do_vfs_ioctl+0x522/0x570
[<ffffffff8130a4b3>] ? file_has_perm+0x83/0xa0
[<ffffffff810f354d>] ? trace_hardirqs_on+0xd/0x10
[<ffffffff811b95ed>] sys_ioctl+0x5d/0xa0
[<ffffffff813663fe>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81faed69>] system_call_fastpath+0x16/0x1b

Reported-and-tested-by: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/core/seq/seq_timer.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/sound/core/seq/seq_timer.c
+++ b/sound/core/seq/seq_timer.c
@@ -290,10 +290,10 @@ int snd_seq_timer_open(struct snd_seq_qu
tid.device = SNDRV_TIMER_GLOBAL_SYSTEM;
err = snd_timer_open(&t, str, &tid, q->queue);
}
- if (err < 0) {
- snd_printk(KERN_ERR "seq fatal error: cannot create timer (%i)\n", err);
- return err;
- }
+ }
+ if (err < 0) {
+ snd_printk(KERN_ERR "seq fatal error: cannot create timer (%i)\n", err);
+ return err;
}
t->callback = snd_seq_timer_interrupt;
t->callback_data = q;