[PATCH] ecryptfs: hold msg ctx list lock when cleaning daemon queue

[Yichong Chen]

ecryptfs_exorcise_daemon() drops queued messages from a dying daemon
without holding ecryptfs_msg_ctx_lists_mux, but
ecryptfs_msg_ctx_alloc_to_free() requires that lock.

Take the list lock while moving the queued contexts back to the free
list to avoid racing with other global msg ctx list users.

Fixes: f66e883eb618 ("eCryptfs: integrate eCryptfs device handle into the module.")
Signed-off-by: Yichong Chen <chenyichong@xxxxxxxxxxxxx>
---
 fs/ecryptfs/messaging.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index 03c60f0850ca..ecdfd965b87e 100644
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -166,6 +166,7 @@ int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
 		mutex_unlock(&daemon->mux);
 		goto out;
 	}
+	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
 	list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
 				 &daemon->msg_ctx_out_queue, daemon_out_list) {
 		list_del(&msg_ctx->daemon_out_list);
@@ -174,6 +175,7 @@ int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
 		       "the out queue of a dying daemon\n", __func__);
 		ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
 	}
+	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 	hlist_del(&daemon->euid_chain);
 	mutex_unlock(&daemon->mux);
 	kfree_sensitive(daemon);
-- 
2.48.1