[PATCH 6.19 83/86] rxrpc: Fix buffer overread in rxgk_do_verify_authenticator()

Greg Kroah-Hartman
2026-04-13T16:06:38Z

From: David Howells <dhowells@redhat.com>

commit f564af387c8c28238f8ebc13314c589d7ba8475d upstream.

Fix rxgk_do_verify_authenticator() to check the buffer size before checking
the nonce.

Fixes: 9d1d2b59341f ("rxrpc: rxgk: Implement the yfs-rxgk security class (GSSAPI)")
Closes: https://sashiko.dev/#/patchset/20260401105614.1696001-10-dhowells@redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260408121252.2249051-20-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/rxrpc/rxgk.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/rxrpc/rxgk.c
+++ b/net/rxrpc/rxgk.c
@@ -1085,6 +1085,9 @@ static int rxgk_do_verify_authenticator(

_enter("");

+ if ((end - p) * sizeof(__be32) < 24)
+ return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
+ rxgk_abort_resp_short_auth);
if (memcmp(p, conn->rxgk.nonce, 20) != 0)
return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
rxgk_abort_resp_bad_nonce);
@@ -1098,7 +1101,7 @@ static int rxgk_do_verify_authenticator(
p += xdr_round_up(app_len) / sizeof(__be32);
if (end - p < 4)
return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
- rxgk_abort_resp_short_applen);
+ rxgk_abort_resp_short_auth);

level = ntohl(*p++);
epoch = ntohl(*p++);