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From:   Vasily Averin <vvs@virtuozzo.com>
Subject: [PATCH v2] nfsd: memory corruption in nfsd4_lock()
To:     "J. Bruce Fields" <bfields@redhat.com>,
        Chuck Lever <chuck.lever@oracle.com>,
        Jeff Layton <jlayton@kernel.org>
Cc:     linux-nfs@vger.kernel.org
References: <7E365A05-4D39-4BF9-8E44-244136173FC7@oracle.com>
Message-ID: <d169e942-03e4-0a4b-8c45-56f4c26cd45c@virtuozzo.com>
Date:   Fri, 27 Mar 2020 07:50:40 +0300
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Dear Chuck,
please use following patch instead.
-----
New struct nfsd4_blocked_lock allocated in find_or_allocate_block()
does not initialized nbl_list and nbl_lru.
If conflock allocation fails rollback can call list_del_init()
access uninitialized fields and corrupt memory.

v2: just initialize nbl_list and nbl_lru right after nbl allocation.

Fixes: 76d348fadff5 ("nfsd: have nfsd4_lock use blocking locks for v4.1+ lock")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
 fs/nfsd/nfs4state.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 369e574c5092..1b2eb6b35d64 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -266,6 +266,8 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
 	if (!nbl) {
 		nbl= kmalloc(sizeof(*nbl), GFP_KERNEL);
 		if (nbl) {
+			INIT_LIST_HEAD(&nbl->nbl_list);
+			INIT_LIST_HEAD(&nbl->nbl_lru);
 			fh_copy_shallow(&nbl->nbl_fh, fh);
 			locks_init_lock(&nbl->nbl_lock);
 			nfsd4_init_cb(&nbl->nbl_cb, lo->lo_owner.so_client,
-- 
2.17.1