From 6929350080f4da292d111a3b33e53138fee51cec Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 22 Apr 2026 17:14:34 +0100 Subject: [PATCH] rxgk: Fix potential integer overflow in length check Fix potential integer overflow in rxgk_extract_token() when checking the length of the ticket. Rather than rounding up the value to be tested (which might overflow), round down the size of the available data. Fixes: 2429a1976481 ("rxrpc: Fix untrusted unsigned subtract") Closes: https://sashiko.dev/#/patchset/20260408121252.2249051-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Jeffrey Altman cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260422161438.2593376-6-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- net/rxrpc/rxgk_app.c | 2 +- net/rxrpc/rxgk_common.h | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/net/rxrpc/rxgk_app.c b/net/rxrpc/rxgk_app.c index 30275cb5ba3e..5587639d60c5 100644 --- a/net/rxrpc/rxgk_app.c +++ b/net/rxrpc/rxgk_app.c @@ -214,7 +214,7 @@ int rxgk_extract_token(struct rxrpc_connection *conn, struct sk_buff *skb, ticket_len = ntohl(container.token_len); ticket_offset = token_offset + sizeof(container); - if (xdr_round_up(ticket_len) > token_len - sizeof(container)) + if (ticket_len > xdr_round_down(token_len - sizeof(container))) goto short_packet; _debug("KVNO %u", kvno); diff --git a/net/rxrpc/rxgk_common.h b/net/rxrpc/rxgk_common.h index 80164d89e19c..1e257d7ab8ec 100644 --- a/net/rxrpc/rxgk_common.h +++ b/net/rxrpc/rxgk_common.h @@ -34,6 +34,7 @@ struct rxgk_context { }; #define xdr_round_up(x) (round_up((x), sizeof(__be32))) +#define xdr_round_down(x) (round_down((x), sizeof(__be32))) #define xdr_object_len(x) (4 + xdr_round_up(x)) /*