From 4a7f62f91933c8ae5308f9127fd8ea48188b6bc3 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 30 Mar 2022 15:39:16 +0100 Subject: rxrpc: Fix call timer start racing with call destruction The rxrpc_call struct has a timer used to handle various timed events relating to a call. This timer can get started from the packet input routines that are run in softirq mode with just the RCU read lock held. Unfortunately, because only the RCU read lock is held - and neither ref or other lock is taken - the call can start getting destroyed at the same time a packet comes in addressed to that call. This causes the timer - which was already stopped - to get restarted. Later, the timer dispatch code may then oops if the timer got deallocated first. Fix this by trying to take a ref on the rxrpc_call struct and, if successful, passing that ref along to the timer. If the timer was already running, the ref is discarded. The timer completion routine can then pass the ref along to the call's work item when it queues it. If the timer or work item where already queued/running, the extra ref is discarded. Fixes: a158bdd3247b ("rxrpc: Fix call timeouts") Reported-by: Marc Dionne Signed-off-by: David Howells Reviewed-by: Marc Dionne Tested-by: Marc Dionne cc: linux-afs@lists.infradead.org Link: http://lists.infradead.org/pipermail/linux-afs/2022-March/005073.html Link: https://lore.kernel.org/r/164865115696.2943015.11097991776647323586.stgit@warthog.procyon.org.uk Signed-off-by: Paolo Abeni --- include/trace/events/rxrpc.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include/trace') diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index e70c90116eda..4a3ab0ed6e06 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -83,12 +83,15 @@ enum rxrpc_call_trace { rxrpc_call_error, rxrpc_call_got, rxrpc_call_got_kernel, + rxrpc_call_got_timer, rxrpc_call_got_userid, rxrpc_call_new_client, rxrpc_call_new_service, rxrpc_call_put, rxrpc_call_put_kernel, rxrpc_call_put_noqueue, + rxrpc_call_put_notimer, + rxrpc_call_put_timer, rxrpc_call_put_userid, rxrpc_call_queued, rxrpc_call_queued_ref, @@ -278,12 +281,15 @@ enum rxrpc_tx_point { EM(rxrpc_call_error, "*E*") \ EM(rxrpc_call_got, "GOT") \ EM(rxrpc_call_got_kernel, "Gke") \ + EM(rxrpc_call_got_timer, "GTM") \ EM(rxrpc_call_got_userid, "Gus") \ EM(rxrpc_call_new_client, "NWc") \ EM(rxrpc_call_new_service, "NWs") \ EM(rxrpc_call_put, "PUT") \ EM(rxrpc_call_put_kernel, "Pke") \ - EM(rxrpc_call_put_noqueue, "PNQ") \ + EM(rxrpc_call_put_noqueue, "PnQ") \ + EM(rxrpc_call_put_notimer, "PnT") \ + EM(rxrpc_call_put_timer, "PTM") \ EM(rxrpc_call_put_userid, "Pus") \ EM(rxrpc_call_queued, "QUE") \ EM(rxrpc_call_queued_ref, "QUR") \ -- cgit