Patch "rxrpc: reject undecryptable rxkad response tickets" has been added to the 6.6-stable tree

[gregkh at linuxfoundation.org]

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

    rxrpc: reject undecryptable rxkad response tickets

to the 6.6-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-reject-undecryptable-rxkad-response-tickets.patch
and it can be found in the queue-6.6 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 fe4447cd95623b1cfacc15f280aab73a6d7340b2 Mon Sep 17 00:00:00 2001
From: Yuqi Xu <xuyuqiabc at gmail.com>
Date: Wed, 8 Apr 2026 13:12:39 +0100
Subject: rxrpc: reject undecryptable rxkad response tickets

From: Yuqi Xu <xuyuqiabc at gmail.com>

commit fe4447cd95623b1cfacc15f280aab73a6d7340b2 upstream.

rxkad_decrypt_ticket() decrypts the RXKAD response ticket and then
parses the buffer as plaintext without checking whether
crypto_skcipher_decrypt() succeeded.

A malformed RESPONSE can therefore use a non-block-aligned ticket
length, make the decrypt operation fail, and still drive the ticket
parser with attacker-controlled bytes.

Check the decrypt result and abort the connection with RXKADBADTICKET
when ticket decryption fails.

Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Reported-by: Yifan Wu <yifanwucs at gmail.com>
Reported-by: Juefei Pu <tomapufckgml at gmail.com>
Co-developed-by: Yuan Tan <yuantan098 at gmail.com>
Signed-off-by: Yuan Tan <yuantan098 at gmail.com>
Suggested-by: Xin Liu <bird at lzu.edu.cn>
Tested-by: Ren Wei <enjou1224z at gmail.com>
Signed-off-by: Yuqi Xu <xuyuqiabc 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: Simon Horman <horms at kernel.org>
cc: linux-afs at lists.infradead.org
cc: stable at kernel.org
Link: https://patch.msgid.link/20260408121252.2249051-12-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 net/rxrpc/rxkad.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -869,6 +869,7 @@ static int rxkad_decrypt_ticket(struct r
 	struct in_addr addr;
 	unsigned int life;
 	time64_t issue, now;
+	int ret;
 	bool little_endian;
 	u8 *p, *q, *name, *end;
 
@@ -888,8 +889,11 @@ static int rxkad_decrypt_ticket(struct r
 	sg_init_one(&sg[0], ticket, ticket_len);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
-	crypto_skcipher_decrypt(req);
+	ret = crypto_skcipher_decrypt(req);
 	skcipher_request_free(req);
+	if (ret < 0)
+		return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO,
+					rxkad_abort_resp_tkt_short);
 
 	p = ticket;
 	end = p + ticket_len;


Patches currently in stable-queue which might be from xuyuqiabc at gmail.com are

queue-6.6/rxrpc-reject-undecryptable-rxkad-response-tickets.patch