From: Yuqi Xu Date: Wed, 8 Apr 2026 12:12:39 +0000 (+0100) Subject: rxrpc: reject undecryptable rxkad response tickets X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fe4447cd95623b1cfacc15f280aab73a6d7340b2;p=thirdparty%2Fkernel%2Flinux.git 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: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both") Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Tested-by: Ren Wei Signed-off-by: Yuqi Xu Signed-off-by: Ren Wei Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman 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 --- diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c index e923d6829008..0f79d694cb08 100644 --- a/net/rxrpc/rxkad.c +++ b/net/rxrpc/rxkad.c @@ -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;