From 773433ec58bc8fd361d7c27607f00d18869322ab Mon Sep 17 00:00:00 2001 From: CKI Backport Bot Date: Tue, 28 Apr 2026 11:53:43 +0000 Subject: [PATCH] rxrpc: fix RESPONSE authenticator parser OOB read JIRA: https://redhat.atlassian.net/browse/RHEL-171457 CVE: CVE-2026-31636 commit 3e3138007887504ee9206d0bfb5acb062c600025 Author: Keenan Dong Date: Wed Apr 8 13:12:40 2026 +0100 rxrpc: fix RESPONSE authenticator parser OOB read rxgk_verify_authenticator() copies auth_len bytes into a temporary buffer and then passes p + auth_len as the parser limit to rxgk_do_verify_authenticator(). Since p is a __be32 *, that inflates the parser end pointer by a factor of four and lets malformed RESPONSE authenticators read past the kmalloc() buffer. Decoded from the original latest-net reproduction logs with scripts/decode_stacktrace.sh: BUG: KASAN: slab-out-of-bounds in rxgk_verify_response() Call Trace: dump_stack_lvl() [lib/dump_stack.c:123] print_report() [mm/kasan/report.c:379 mm/kasan/report.c:482] kasan_report() [mm/kasan/report.c:597] rxgk_verify_response() [net/rxrpc/rxgk.c:1103 net/rxrpc/rxgk.c:1167 net/rxrpc/rxgk.c:1274] rxrpc_process_connection() [net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364 net/rxrpc/conn_event.c:386] process_one_work() [kernel/workqueue.c:3281] worker_thread() [kernel/workqueue.c:3353 kernel/workqueue.c:3440] kthread() [kernel/kthread.c:436] ret_from_fork() [arch/x86/kernel/process.c:164] Allocated by task 54: rxgk_verify_response() [include/linux/slab.h:954 net/rxrpc/rxgk.c:1155 net/rxrpc/rxgk.c:1274] rxrpc_process_connection() [net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364 net/rxrpc/conn_event.c:386] Convert the byte count to __be32 units before constructing the parser limit. Fixes: 9d1d2b59341f ("rxrpc: rxgk: Implement the yfs-rxgk security class (GSSAPI)") Signed-off-by: Keenan Dong Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: Willy Tarreau cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260408121252.2249051-13-dhowells@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: CKI Backport Bot diff --git a/net/rxrpc/rxgk.c b/net/rxrpc/rxgk.c index dce5a3d8a964..8d17b49e4f13 100644 --- a/net/rxrpc/rxgk.c +++ b/net/rxrpc/rxgk.c @@ -1164,7 +1164,8 @@ static int rxgk_verify_authenticator(struct rxrpc_connection *conn, } p = auth; - ret = rxgk_do_verify_authenticator(conn, krb5, skb, p, p + auth_len); + ret = rxgk_do_verify_authenticator(conn, krb5, skb, p, + p + auth_len / sizeof(*p)); error: kfree(auth); return ret; -- 2.50.1 (Apple Git-155)