From 69e4186773c6445b258fb45b6e1df18df831ec45 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 8 Jul 2025 22:15:03 +0100 Subject: [PATCH 1/2] rxrpc: Fix bug due to prealloc collision When userspace is using AF_RXRPC to provide a server, it has to preallocate incoming calls and assign to them call IDs that will be used to thread related recvmsg() and sendmsg() together. The preallocated call IDs will automatically be attached to calls as they come in until the pool is empty. To the kernel, the call IDs are just arbitrary numbers, but userspace can use the call ID to hold a pointer to prepared structs. In any case, the user isn't permitted to create two calls with the same call ID (call IDs become available again when the call ends) and EBADSLT should result from sendmsg() if an attempt is made to preallocate a call with an in-use call ID. However, the cleanup in the error handling will trigger both assertions in rxrpc_cleanup_call() because the call isn't marked complete and isn't marked as having been released. Fix this by setting the call state in rxrpc_service_prealloc_one() and then marking it as being released before calling the cleanup function. Fixes: 00e907127e6f ("rxrpc: Preallocate peers, conns and calls for incoming service requests") Reported-by: Junvyyang, Tencent Zhuque Lab Signed-off-by: David Howells cc: LePremierHomme cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250708211506.2699012-2-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- net/rxrpc/call_accept.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c index a4b363b47cca..7271977b1683 100644 --- a/net/rxrpc/call_accept.c +++ b/net/rxrpc/call_accept.c @@ -149,6 +149,7 @@ static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx, id_in_use: write_unlock(&rx->call_lock); + rxrpc_prefail_call(call, RXRPC_CALL_LOCAL_ERROR, -EBADSLT); rxrpc_cleanup_call(call); _leave(" = -EBADSLT"); return -EBADSLT; From 880a88f318cf1d2a0f4c0a7ff7b07e2062b434a4 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 8 Jul 2025 22:15:04 +0100 Subject: [PATCH 2/2] rxrpc: Fix oops due to non-existence of prealloc backlog struct If an AF_RXRPC service socket is opened and bound, but calls are preallocated, then rxrpc_alloc_incoming_call() will oops because the rxrpc_backlog struct doesn't get allocated until the first preallocation is made. Fix this by returning NULL from rxrpc_alloc_incoming_call() if there is no backlog struct. This will cause the incoming call to be aborted. Reported-by: Junvyyang, Tencent Zhuque Lab Suggested-by: Junvyyang, Tencent Zhuque Lab Signed-off-by: David Howells cc: LePremierHomme cc: Marc Dionne cc: Willy Tarreau cc: Simon Horman cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250708211506.2699012-3-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- net/rxrpc/call_accept.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c index 7271977b1683..49fccee1a726 100644 --- a/net/rxrpc/call_accept.c +++ b/net/rxrpc/call_accept.c @@ -255,6 +255,9 @@ static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx, unsigned short call_tail, conn_tail, peer_tail; unsigned short call_count, conn_count; + if (!b) + return NULL; + /* #calls >= #conns >= #peers must hold true. */ call_head = smp_load_acquire(&b->call_backlog_head); call_tail = b->call_backlog_tail;