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rxrpc: Fix NULL pointer deref due to call->conn being cleared on disconnect

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[ Upstream commit 5273a191dc ]

When a call is disconnected, the connection pointer from the call is
cleared to make sure it isn't used again and to prevent further attempted
transmission for the call.  Unfortunately, there might be a daemon trying
to use it at the same time to transmit a packet.

Fix this by keeping call->conn set, but setting a flag on the call to
indicate disconnection instead.

Remove also the bits in the transmission functions where the conn pointer is
checked and a ref taken under spinlock as this is now redundant.

Fixes: 8d94aa381d ("rxrpc: Calls shouldn't hold socket refs")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Howells
2020-01-30 21:50:36 +00:00
committed by Greg Kroah-Hartman
parent 843e115de4
commit 269a3c472a
5 changed files with 15 additions and 24 deletions
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3
net/rxrpc/conn_client.c
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@@ -785,6 +785,7 @@ void rxrpc_disconnect_client_call(struct rxrpc_call *call)
u32 cid;
spin_lock(&conn->channel_lock);
set_bit(RXRPC_CALL_DISCONNECTED, &call->flags);
cid = call->cid;
if (cid) {
@@ -792,7 +793,6 @@ void rxrpc_disconnect_client_call(struct rxrpc_call *call)
chan = &conn->channels[channel];
}
trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
call->conn = NULL;
/* Calls that have never actually been assigned a channel can simply be
* discarded. If the conn didn't get used either, it will follow
@@ -908,7 +908,6 @@ out:
spin_unlock(&rxnet->client_conn_cache_lock);
out_2:
spin_unlock(&conn->channel_lock);
rxrpc_put_connection(conn);
_leave("");
return;