From nobody Wed Feb 11 14:20:43 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D551C05027 for ; Tue, 14 Mar 2023 19:04:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231197AbjCNTET (ORCPT ); Tue, 14 Mar 2023 15:04:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231247AbjCNTEM (ORCPT ); Tue, 14 Mar 2023 15:04:12 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29087193C5; Tue, 14 Mar 2023 12:03:31 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A6356B81B61; Tue, 14 Mar 2023 19:03:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6AFBDC433D2; Tue, 14 Mar 2023 19:03:11 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1pc9vS-009tyf-0p; Tue, 14 Mar 2023 15:03:10 -0400 Message-ID: <20230314190310.070032647@goodmis.org> User-Agent: quilt/0.66 Date: Tue, 14 Mar 2023 15:02:39 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , stable@vger.kernel.org, Chen Zhongjin Subject: [for-linus][PATCH 3/5] ftrace: Fix invalid address access in lookup_rec() when index is 0 References: <20230314190236.203370742@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Chen Zhongjin KASAN reported follow problem: BUG: KASAN: use-after-free in lookup_rec Read of size 8 at addr ffff000199270ff0 by task modprobe CPU: 2 Comm: modprobe Call trace: kasan_report __asan_load8 lookup_rec ftrace_location arch_check_ftrace_location check_kprobe_address_safe register_kprobe When checking pg->records[pg->index - 1].ip in lookup_rec(), it can get a pg which is newly added to ftrace_pages_start in ftrace_process_locs(). Before the first pg->index++, index is 0 and accessing pg->records[-1].ip will cause this problem. Don't check the ip when pg->index is 0. Link: https://lore.kernel.org/linux-trace-kernel/20230309080230.36064-1-che= nzhongjin@huawei.com Cc: stable@vger.kernel.org Fixes: 9644302e3315 ("ftrace: Speed up search by skipping pages by address") Suggested-by: Steven Rostedt (Google) Signed-off-by: Chen Zhongjin Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ftrace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 750aa3f08b25..a47f7d93e32d 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1537,7 +1537,8 @@ static struct dyn_ftrace *lookup_rec(unsigned long st= art, unsigned long end) key.flags =3D end; /* overload flags, as it is unsigned long */ =20 for (pg =3D ftrace_pages_start; pg; pg =3D pg->next) { - if (end < pg->records[0].ip || + if (pg->index =3D=3D 0 || + end < pg->records[0].ip || start >=3D (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE)) continue; rec =3D bsearch(&key, pg->records, pg->index, --=20 2.39.1