From 0e50d999903c009b6a9cd2277c82d6798d982e31 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 24 Dec 2022 14:49:00 +0000 Subject: [PATCH] rxrpc: Fix a couple of potential use-after-frees At the end of rxrpc_recvmsg(), if a call is found, the call is put and then a trace line is emitted referencing that call in a couple of places - but the call may have been deallocated by the time those traces happen. Fix this by stashing the call debug_id in a variable and passing that to the tracepoint rather than the call pointer. Fixes: 849979051cbc ("rxrpc: Add a tracepoint to follow what recvmsg does") Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org Signed-off-by: David S. Miller --- include/trace/events/rxrpc.h | 6 +++--- net/rxrpc/recvmsg.c | 14 ++++++++------ 2 files changed, 11 insertions(+), 9 deletions(-) diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index c6cfed00d0c6..5f9dd7389536 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -1062,10 +1062,10 @@ TRACE_EVENT(rxrpc_receive, ); TRACE_EVENT(rxrpc_recvmsg, - TP_PROTO(struct rxrpc_call *call, enum rxrpc_recvmsg_trace why, + TP_PROTO(unsigned int call_debug_id, enum rxrpc_recvmsg_trace why, int ret), - TP_ARGS(call, why, ret), + TP_ARGS(call_debug_id, why, ret), TP_STRUCT__entry( __field(unsigned int, call ) @@ -1074,7 +1074,7 @@ TRACE_EVENT(rxrpc_recvmsg, ), TP_fast_assign( - __entry->call = call ? call->debug_id : 0; + __entry->call = call_debug_id; __entry->why = why; __entry->ret = ret; ), diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c index 36b25d003cf0..6ebd6440a2b7 100644 --- a/net/rxrpc/recvmsg.c +++ b/net/rxrpc/recvmsg.c @@ -388,13 +388,14 @@ int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, struct rxrpc_call *call; struct rxrpc_sock *rx = rxrpc_sk(sock->sk); struct list_head *l; + unsigned int call_debug_id = 0; size_t copied = 0; long timeo; int ret; DEFINE_WAIT(wait); - trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0); + trace_rxrpc_recvmsg(0, rxrpc_recvmsg_enter, 0); if (flags & (MSG_OOB | MSG_TRUNC)) return -EOPNOTSUPP; @@ -431,7 +432,7 @@ try_again: if (list_empty(&rx->recvmsg_q)) { if (signal_pending(current)) goto wait_interrupted; - trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait, 0); + trace_rxrpc_recvmsg(0, rxrpc_recvmsg_wait, 0); timeo = schedule_timeout(timeo); } finish_wait(sk_sleep(&rx->sk), &wait); @@ -450,7 +451,8 @@ try_again: rxrpc_get_call(call, rxrpc_call_get_recvmsg); write_unlock(&rx->recvmsg_lock); - trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0); + call_debug_id = call->debug_id; + trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_dequeue, 0); /* We're going to drop the socket lock, so we need to lock the call * against interference by sendmsg. @@ -531,7 +533,7 @@ try_again: error_unlock_call: mutex_unlock(&call->user_mutex); rxrpc_put_call(call, rxrpc_call_put_recvmsg); - trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, ret); + trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_return, ret); return ret; error_requeue_call: @@ -539,14 +541,14 @@ error_requeue_call: write_lock(&rx->recvmsg_lock); list_add(&call->recvmsg_link, &rx->recvmsg_q); write_unlock(&rx->recvmsg_lock); - trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0); + trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_requeue, 0); } else { rxrpc_put_call(call, rxrpc_call_put_recvmsg); } error_no_call: release_sock(&rx->sk); error_trace: - trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, ret); + trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_return, ret); return ret; wait_interrupted: