linux-kernel - [34-longterm 056/260] ALSA: seq/oss - Fix double-free at error path of snd_seq_oss

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Message-Id: <1293952756-15010-57-git-send-email-paul.gortmaker@windriver.com>
Date:	Sun,  2 Jan 2011 02:15:52 -0500
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Takashi Iwai <tiwai@...e.de>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 056/260] ALSA: seq/oss - Fix double-free at error path of snd_seq_oss_open()

From: Takashi Iwai <tiwai@...e.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@...xchg8b.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.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

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