Commit a6f951dd authored by Trond Myklebust's avatar Trond Myklebust

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

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 70cc6487
(locks: make ->lock release private data before returning in GETLK case)
Reported-by: default avatarWeston Andros Adamson <dros@netapp.com>
Reported-by: default avatarJorge Mora <mora@netapp.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: <stable@vger.kernel.org> #2.6.22+
parent f9273188
...@@ -5106,6 +5106,7 @@ static int _nfs4_proc_getlk(struct nfs4_state *state, int cmd, struct file_lock ...@@ -5106,6 +5106,7 @@ static int _nfs4_proc_getlk(struct nfs4_state *state, int cmd, struct file_lock
status = 0; status = 0;
} }
request->fl_ops->fl_release_private(request); request->fl_ops->fl_release_private(request);
request->fl_ops = NULL;
out: out:
return status; return status;
} }
......
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