Patch "NFSv4: Fix a use-after-free situation in _nfs4_proc_getlk()" has been added to the 3.12-stable tree

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This is a note to let you know that I've just added the patch titled

    NFSv4: Fix a use-after-free situation in _nfs4_proc_getlk()

to the 3.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsv4-fix-a-use-after-free-situation-in-_nfs4_proc_getlk.patch
and it can be found in the queue-3.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From a6f951ddbdfb7bd87d31a44f61abe202ed6ce57f Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Date: Tue, 1 Oct 2013 14:24:58 -0400
Subject: NFSv4: Fix a use-after-free situation in _nfs4_proc_getlk()

From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

commit a6f951ddbdfb7bd87d31a44f61abe202ed6ce57f upstream.

In nfs4_proc_getlk(), when some error causes a retry of the call to
_nfs4_proc_getlk(), we can end up with Oopses of the form

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000134
 IP: [<ffffffff8165270e>] _raw_spin_lock+0xe/0x30
<snip>
 Call Trace:
  [<ffffffff812f287d>] _atomic_dec_and_lock+0x4d/0x70
  [<ffffffffa053c4f2>] nfs4_put_lock_state+0x32/0xb0 [nfsv4]
  [<ffffffffa053c585>] nfs4_fl_release_lock+0x15/0x20 [nfsv4]
  [<ffffffffa0522c06>] _nfs4_proc_getlk.isra.40+0x146/0x170 [nfsv4]
  [<ffffffffa052ad99>] nfs4_proc_lock+0x399/0x5a0 [nfsv4]

The problem is that we don't clear the request->fl_ops after the first
try and so when we retry, nfs4_set_lock_state() exits early without
setting the lock stateid.
Regression introduced by commit 70cc6487a4e08b8698c0e2ec935fb48d10490162
(locks: make ->lock release private data before returning in GETLK case)

Reported-by: Weston Andros Adamson <dros@xxxxxxxxxx>
Reported-by: Jorge Mora <mora@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/nfs/nfs4proc.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5106,6 +5106,7 @@ static int _nfs4_proc_getlk(struct nfs4_
 			status = 0;
 	}
 	request->fl_ops->fl_release_private(request);
+	request->fl_ops = NULL;
 out:
 	return status;
 }


Patches currently in stable-queue which might be from Trond.Myklebust@xxxxxxxxxx are

queue-3.12/nfsv4.2-fix-a-mismatch-between-linux-labeled-nfs-and-the-nfsv4.2-spec.patch
queue-3.12/nfs-fix-oops-when-trying-to-set-selinux-label.patch
queue-3.12/nfs-fix-a-missing-initialisation-when-reading-the-selinux-label.patch
queue-3.12/nfsv4-fix-a-use-after-free-situation-in-_nfs4_proc_getlk.patch
queue-3.12/nfs-fix-inverted-test-for-delegation-in-nfs4_reclaim_open_state.patch
queue-3.12/nfsv4-fix-null-dereference-in-open-recover.patch
queue-3.12/nfs-don-t-retry-detect_trunking-with-rpc_auth_unix-more-than-once.patch
queue-3.12/nfsv4-don-t-reprocess-cached-open-claim_previous.patch
queue-3.12/nfsv4-fix-state-reference-counting-in-_nfs4_opendata_reclaim_to_nfs4_state.patch
queue-3.12/nfsv4-don-t-fail-on-missing-fattr-in-open-recover.patch
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