[34-longterm 093/247] ocfs2_connection_find() returns pointer to bad structure

Paul Gortmaker
2011-06-23T17:36:23Z

From: dann frazier <dann.frazier@canonical.com>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.
-------------------

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@canonical.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
fs/ocfs2/stack_user.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
index 2dc57bc..22db114 100644
--- a/fs/ocfs2/stack_user.c
+++ b/fs/ocfs2/stack_user.c
@@ -191,7 +191,7 @@ static struct ocfs2_live_connection *ocfs2_connection_find(const char *name)
return c;
}

- return c;
+ return NULL;
}

/*
--
1.7.4.4