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authorDavid Howells <dhowells@redhat.com>2022-04-13 11:16:25 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-04-27 13:50:46 +0200
commitf10e5c9f226cf90fcf796e590b75dea85d3bdfd8 (patch)
tree4bf8e4c8e539c90ee1ac94bf2405d28730c09b89 /net/rxrpc
parent9a9c481593650bbe4066e2185de6b68a82a4110f (diff)
rxrpc: Restore removed timer deletion
[ Upstream commit ee3b0826b4764f6c13ad6db67495c5a1c38e9025 ] A recent patch[1] from Eric Dumazet flipped the order in which the keepalive timer and the keepalive worker were cancelled in order to fix a syzbot reported issue[2]. Unfortunately, this enables the mirror image bug whereby the timer races with rxrpc_exit_net(), restarting the worker after it has been cancelled: CPU 1 CPU 2 =============== ===================== if (rxnet->live) <INTERRUPT> rxnet->live = false; cancel_work_sync(&rxnet->peer_keepalive_work); rxrpc_queue_work(&rxnet->peer_keepalive_work); del_timer_sync(&rxnet->peer_keepalive_timer); Fix this by restoring the removed del_timer_sync() so that we try to remove the timer twice. If the timer runs again, it should see ->live == false and not restart the worker. Fixes: 1946014ca3b1 ("rxrpc: fix a race in rxrpc_exit_net()") Signed-off-by: David Howells <dhowells@redhat.com> cc: Eric Dumazet <edumazet@google.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/20220404183439.3537837-1-eric.dumazet@gmail.com/ [1] Link: https://syzkaller.appspot.com/bug?extid=724378c4bb58f703b09a [2] Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/rxrpc')
-rw-r--r--net/rxrpc/net_ns.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/rxrpc/net_ns.c b/net/rxrpc/net_ns.c
index 9a76b74af37b..91a503871116 100644
--- a/net/rxrpc/net_ns.c
+++ b/net/rxrpc/net_ns.c
@@ -116,7 +116,9 @@ static __net_exit void rxrpc_exit_net(struct net *net)
struct rxrpc_net *rxnet = rxrpc_net(net);
rxnet->live = false;
+ del_timer_sync(&rxnet->peer_keepalive_timer);
cancel_work_sync(&rxnet->peer_keepalive_work);
+ /* Remove the timer again as the worker may have restarted it. */
del_timer_sync(&rxnet->peer_keepalive_timer);
rxrpc_destroy_all_calls(rxnet);
rxrpc_destroy_all_connections(rxnet);