[PATCH] [114/275] ocfs2_connection_find() returns pointer to bad structure

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: dann frazier <dann.frazier@xxxxxxxxxxxxx>

commit 226291aa4641fa13cb5dec3bcb3379faa83009e2 upstream.

If ocfs2_live_connection_list is empty, ocfs2_connection_find() will return
a pointer to the LIST_HEAD, cast as a ocfs2_live_connection. This can cause
an oops when ocfs2_control_send_down() dereferences c->oc_conn:

Call Trace:
  [<ffffffffa00c2a3c>] ocfs2_control_message+0x28c/0x2b0 [ocfs2_stack_user]
  [<ffffffffa00c2a95>] ocfs2_control_write+0x35/0xb0 [ocfs2_stack_user]
  [<ffffffff81143a88>] vfs_write+0xb8/0x1a0
  [<ffffffff8155cc13>] ? do_page_fault+0x153/0x3b0
  [<ffffffff811442f1>] sys_write+0x51/0x80
  [<ffffffff810121b2>] system_call_fastpath+0x16/0x1b

Fix by explicitly returning NULL if no match is found.

Signed-off-by: dann frazier <dann.frazier@xxxxxxxxxxxxx>
Signed-off-by: Joel Becker <joel.becker@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 fs/ocfs2/stack_user.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.35.y/fs/ocfs2/stack_user.c
===================================================================
--- linux-2.6.35.y.orig/fs/ocfs2/stack_user.c	2011-03-29 22:51:23.042133577 -0700
+++ linux-2.6.35.y/fs/ocfs2/stack_user.c	2011-03-29 23:03:00.557285910 -0700
@@ -191,7 +191,7 @@
 			return c;
 	}
 
-	return c;
+	return NULL;
 }
 
 /*
--
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