Patch "rxrpc: serialize kernel accept preallocation with socket teardown" has been added to the 6.18-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    rxrpc: serialize kernel accept preallocation with socket teardown

to the 6.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     rxrpc-serialize-kernel-accept-preallocation-with-socket-teardown.patch
and it can be found in the queue-6.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From dc175389b18c29a5303ee83169ec653adfae3e17 Mon Sep 17 00:00:00 2001
From: Li Daming <d4n.for.sec at gmail.com>
Date: Tue, 9 Jun 2026 15:09:09 +0100
Subject: rxrpc: serialize kernel accept preallocation with socket teardown

From: Li Daming <d4n.for.sec at gmail.com>

commit dc175389b18c29a5303ee83169ec653adfae3e17 upstream.

rxrpc_kernel_charge_accept() reads rx->backlog without any
socket/backlog synchronization and passes that raw pointer into
rxrpc_service_prealloc_one(). A concurrent rxrpc_discard_prealloc()
sets rx->backlog = NULL and frees the backlog rings, so a kernel
preallocation worker can keep using a freed struct rxrpc_backlog
while updating *_backlog_head/tail and array slots.

Serialize the state check and backlog lookup with the socket lock,
and reject kernel preallocation once teardown has disabled
listening or discarded the service backlog.

Fixes: 00e907127e6f ("rxrpc: Preallocate peers, conns and calls for incoming service requests")
Reported-by: Yuan Tan <yuantan098 at gmail.com>
Reported-by: Yifan Wu <yifanwucs at gmail.com>
Reported-by: Juefei Pu <tomapufckgml at gmail.com>
Reported-by: Xin Liu <bird at lzu.edu.cn>
Signed-off-by: Li Daming <d4n.for.sec at gmail.com>
Signed-off-by: Ren Wei <n05ec at lzu.edu.cn>
Signed-off-by: David Howells <dhowells at redhat.com>
cc: Marc Dionne <marc.dionne at auristor.com>
cc: Jeffrey Altman <jaltman at auristor.com>
cc: Simon Horman <horms at kernel.org>
cc: linux-afs at lists.infradead.org
cc: stable at kernel.org
Link: https://patch.msgid.link/20260609140911.838677-6-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 net/rxrpc/call_accept.c |   25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

--- a/net/rxrpc/call_accept.c
+++ b/net/rxrpc/call_accept.c
@@ -471,13 +471,26 @@ int rxrpc_kernel_charge_accept(struct so
 			       unsigned long user_call_ID, gfp_t gfp,
 			       unsigned int debug_id)
 {
-	struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
-	struct rxrpc_backlog *b = rx->backlog;
+	struct rxrpc_backlog *b;
+	struct rxrpc_sock *rx;
+	struct sock *sk;
+	int ret;
 
-	if (sock->sk->sk_state == RXRPC_CLOSE)
-		return -ESHUTDOWN;
+	sk = sock->sk;
+	rx = rxrpc_sk(sk);
 
-	return rxrpc_service_prealloc_one(rx, b, notify_rx, user_call_ID,
-					  gfp, debug_id);
+	lock_sock(sk);
+	if (sk->sk_state != RXRPC_SERVER_LISTENING || !rx->backlog) {
+		ret = -ESHUTDOWN;
+		goto out;
+	}
+
+	b = rx->backlog;
+	ret = rxrpc_service_prealloc_one(rx, b, notify_rx, user_call_ID,
+					 gfp, debug_id);
+
+out:
+	release_sock(sk);
+	return ret;
 }
 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);


Patches currently in stable-queue which might be from d4n.for.sec at gmail.com are

queue-6.18/afs-fix-further-netns-teardown-to-cancel-the-preallocation-charger.patch
queue-6.18/afs-fix-netns-teardown-to-cancel-the-preallocation-charger.patch
queue-6.18/rxrpc-serialize-kernel-accept-preallocation-with-socket-teardown.patch
queue-6.18/afs-fix-uncancelled-rxrpc-oob-message-handler.patch