Commit fe4447cd authored Apr 08, 2026 by Yuqi Xu Committed by Jakub Kicinski Apr 08, 2026

rxrpc: reject undecryptable rxkad response tickets



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: 17926a79 ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Co-developed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Yuan Tan <yuantan098@gmail.com>
Suggested-by: Xin Liu <bird@lzu.edu.cn>
Tested-by: Ren Wei <enjou1224z@gmail.com>
Signed-off-by: Yuqi Xu <xuyuqiabc@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260408121252.2249051-12-dhowells@redhat.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 6331f1b2

net/rxrpc/rxkad.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -958,6 +958,7 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
		struct in_addr addr;
		unsigned int life;
		time64_t issue, now;
		int ret;
		bool little_endian;
		u8 p, q, name, end;

		@@ -977,8 +978,11 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
		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;