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lockd: fix NULL dereference on lockowner allocation failure

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commit 4c7fc129db upstream.

nlmclnt_locks_init_private() installs NLM file lock operations even when
nlmclnt_find_lockowner() fails to allocate a lockowner. nlmclnt_proc()
then returns -ENOMEM, but the VFS still tears down the partially
initialized file_lock and calls locks_release_private().

That invokes nlmclnt_locks_release_private(), which dereferences
fl->fl_u.nfs_fl.owner and crashes because the owner was never installed.

Clear fl_ops before attempting to initialize the NLM private state, and
install the NLM lock operations only after a lockowner has been allocated
successfully.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Shuangpeng Bai
2026-09-07 17:18:15 +02:00
committed by Greg Kroah-Hartman
parent c24bdb7df2
commit 07adfbb3de
1 changed files with 3 additions and 0 deletions
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fs/lockd/clntproc.c
+3
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@@ -487,9 +487,12 @@ static const struct file_lock_operations nlmclnt_lock_ops = {
static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
{
fl->fl_u.nfs_fl.state = 0;
fl->fl_ops = NULL;
fl->fl_u.nfs_fl.owner = nlmclnt_find_lockowner(host,
fl->c.flc_owner);
INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
if (!fl->fl_u.nfs_fl.owner)
return;
fl->fl_ops = &nlmclnt_lock_ops;
}