From: David Howells dhowells@redhat.com
[ Upstream commit 2b5fdc0f5caa505afe34d608e2eefadadf2ee67a ]
Inside the loop in rxrpc_wait_to_be_connected() it checks call->error to see if it should exit the loop without first checking the call state. This is probably safe as if call->error is set, the call is dead anyway, but we should probably wait for the call state to have been set to completion first, lest it cause surprise on the way out.
Fix this by only accessing call->error if the call is complete. We don't actually need to access the error inside the loop as we'll do that after.
This caused the following report:
BUG: KCSAN: data-race in rxrpc_send_data / rxrpc_set_call_completion
write to 0xffff888159cf3c50 of 4 bytes by task 25673 on cpu 1: rxrpc_set_call_completion+0x71/0x1c0 net/rxrpc/call_state.c:22 rxrpc_send_data_packet+0xba9/0x1650 net/rxrpc/output.c:479 rxrpc_transmit_one+0x1e/0x130 net/rxrpc/output.c:714 rxrpc_decant_prepared_tx net/rxrpc/call_event.c:326 [inline] rxrpc_transmit_some_data+0x496/0x600 net/rxrpc/call_event.c:350 rxrpc_input_call_event+0x564/0x1220 net/rxrpc/call_event.c:464 rxrpc_io_thread+0x307/0x1d80 net/rxrpc/io_thread.c:461 kthread+0x1ac/0x1e0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
read to 0xffff888159cf3c50 of 4 bytes by task 25672 on cpu 0: rxrpc_send_data+0x29e/0x1950 net/rxrpc/sendmsg.c:296 rxrpc_do_sendmsg+0xb7a/0xc20 net/rxrpc/sendmsg.c:726 rxrpc_sendmsg+0x413/0x520 net/rxrpc/af_rxrpc.c:565 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x375/0x4c0 net/socket.c:2501 ___sys_sendmsg net/socket.c:2555 [inline] __sys_sendmmsg+0x263/0x500 net/socket.c:2641 __do_sys_sendmmsg net/socket.c:2670 [inline] __se_sys_sendmmsg net/socket.c:2667 [inline] __x64_sys_sendmmsg+0x57/0x60 net/socket.c:2667 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
value changed: 0x00000000 -> 0xffffffea
Fixes: 9d35d880e0e4 ("rxrpc: Move client call connection to the I/O thread") Reported-by: syzbot+ebc945fdb4acd72cba78@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000e7c6d205fa10a3cd@google.com/ Signed-off-by: David Howells dhowells@redhat.com cc: Marc Dionne marc.dionne@auristor.com cc: Dmitry Vyukov dvyukov@google.com cc: "David S. Miller" davem@davemloft.net cc: Eric Dumazet edumazet@google.com cc: Jakub Kicinski kuba@kernel.org cc: Paolo Abeni pabeni@redhat.com cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org cc: netdev@vger.kernel.org Link: https://lore.kernel.org/r/508133.1682427395@warthog.procyon.org.uk Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/rxrpc/sendmsg.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index da49fcf1c4567..6caa47d352ed6 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -50,15 +50,11 @@ static int rxrpc_wait_to_be_connected(struct rxrpc_call *call, long *timeo) _enter("%d", call->debug_id);
if (rxrpc_call_state(call) != RXRPC_CALL_CLIENT_AWAIT_CONN) - return call->error; + goto no_wait;
add_wait_queue_exclusive(&call->waitq, &myself);
for (;;) { - ret = call->error; - if (ret < 0) - break; - switch (call->interruptibility) { case RXRPC_INTERRUPTIBLE: case RXRPC_PREINTERRUPTIBLE: @@ -69,10 +65,9 @@ static int rxrpc_wait_to_be_connected(struct rxrpc_call *call, long *timeo) set_current_state(TASK_UNINTERRUPTIBLE); break; } - if (rxrpc_call_state(call) != RXRPC_CALL_CLIENT_AWAIT_CONN) { - ret = call->error; + + if (rxrpc_call_state(call) != RXRPC_CALL_CLIENT_AWAIT_CONN) break; - } if ((call->interruptibility == RXRPC_INTERRUPTIBLE || call->interruptibility == RXRPC_PREINTERRUPTIBLE) && signal_pending(current)) { @@ -85,6 +80,7 @@ static int rxrpc_wait_to_be_connected(struct rxrpc_call *call, long *timeo) remove_wait_queue(&call->waitq, &myself); __set_current_state(TASK_RUNNING);
+no_wait: if (ret == 0 && rxrpc_call_is_complete(call)) ret = call->error;