From a6f951ddbdfb7bd87d31a44f61abe202ed6ce57f Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 1 Oct 2013 14:24:58 -0400 Subject: [PATCH] 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: [] _raw_spin_lock+0xe/0x30 Call Trace: [] _atomic_dec_and_lock+0x4d/0x70 [] nfs4_put_lock_state+0x32/0xb0 [nfsv4] [] nfs4_fl_release_lock+0x15/0x20 [nfsv4] [] _nfs4_proc_getlk.isra.40+0x146/0x170 [nfsv4] [] 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 Reported-by: Jorge Mora Signed-off-by: Trond Myklebust Cc: #2.6.22+ --- fs/nfs/nfs4proc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index d53d678..d2b4845e 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -5106,6 +5106,7 @@ static int _nfs4_proc_getlk(struct nfs4_state *state, int cmd, struct file_lock status = 0; } request->fl_ops->fl_release_private(request); + request->fl_ops = NULL; out: return status; } -- 2.7.4