NFSD: fix use-after-free in nfsd4_ssc_setup_dul()

[ Upstream commit e6cf91b7b47ff82b624bdfe2fdcde32bb52e71dd ]

If signal_pending() returns true, schedule_timeout() will not be executed,
causing the waiting task to remain in the wait queue.
Fixed by adding a call to finish_wait(), which ensures that the waiting
task will always be removed from the wait queue.

Fixes: f4e44b393389 ("NFSD: delay unmount source's export after inter-server copy completed.")
Signed-off-by: Xingyuan Mo <hdthky0@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 09dd70f..0a900b9 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1205,6 +1205,7 @@ try_again:
                        /* allow 20secs for mount/unmount for now - revisit */
                        if (signal_pending(current) ||
                                        (schedule_timeout(20*HZ) == 0)) {
+                               finish_wait(&nn->nfsd_ssc_waitq, &wait);
                                kfree(work);
                                return nfserr_eagain;
                        }