[34-longterm 056/260] ALSA: seq/oss - Fix double-free at error path of snd_seq_oss_open()

Paul Gortmaker
2011-01-02T08:05:56Z

From: Takashi Iwai <tiwai@suse.de>

commit 27f7ad53829f79e799a253285318bff79ece15bd upstream.

The error handling in snd_seq_oss_open() has several bad codes that
do dereferecing released pointers and double-free of kmalloc'ed data.
The object dp is release in free_devinfo() that is called via
private_free callback. The rest shouldn't touch this object any more.

The patch changes delete_port() to call kfree() in any case, and gets
rid of unnecessary calls of destructors in snd_seq_oss_open().

Fixes CVE-2010-3080.

Reported-and-tested-by: Tavis Ormandy <taviso@cmpxchg8b.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
sound/core/seq/oss/seq_oss_init.c | 9 ++++-----
1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/sound/core/seq/oss/seq_oss_init.c b/sound/core/seq/oss/seq_oss_init.c
index 6857122..69cd7b3 100644
--- a/sound/core/seq/oss/seq_oss_init.c
+++ b/sound/core/seq/oss/seq_oss_init.c
@@ -281,13 +281,10 @@ snd_seq_oss_open(struct file *file, int level)
return 0;

_error:
- snd_seq_oss_writeq_delete(dp->writeq);
- snd_seq_oss_readq_delete(dp->readq);
snd_seq_oss_synth_cleanup(dp);
snd_seq_oss_midi_cleanup(dp);
- delete_port(dp);
delete_seq_queue(dp->queue);
- kfree(dp);
+ delete_port(dp);

return rc;
}
@@ -350,8 +347,10 @@ create_port(struct seq_oss_devinfo *dp)
static int
delete_port(struct seq_oss_devinfo *dp)
{
- if (dp->port < 0)
+ if (dp->port < 0) {
+ kfree(dp);
return 0;
+ }

debug_printk(("delete_port %i\n", dp->port));
return snd_seq_event_port_detach(dp->cseq, dp->port);
--
1.7.3.3