From nobody Mon Feb 9 10:48:03 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1553188473408221.90688960926275; Thu, 21 Mar 2019 10:14:33 -0700 (PDT) Received: from localhost ([127.0.0.1]:42449 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h71Gt-00053g-T8 for importer@patchew.org; Thu, 21 Mar 2019 13:14:27 -0400 Received: from eggs.gnu.org ([209.51.188.92]:52462) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h71EZ-0003US-Mt for qemu-devel@nongnu.org; Thu, 21 Mar 2019 13:12:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h71BI-0002T6-Rj for qemu-devel@nongnu.org; Thu, 21 Mar 2019 13:08:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42200) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h71BI-0002R6-Gc for qemu-devel@nongnu.org; Thu, 21 Mar 2019 13:08:40 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C81ADC057F4F for ; Thu, 21 Mar 2019 17:08:39 +0000 (UTC) Received: from localhost (ovpn-117-168.ams2.redhat.com [10.36.117.168]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4D99F6014C; Thu, 21 Mar 2019 17:08:37 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Thu, 21 Mar 2019 17:08:30 +0000 Message-Id: <20190321170831.6539-2-stefanha@redhat.com> In-Reply-To: <20190321170831.6539-1-stefanha@redhat.com> References: <20190321170831.6539-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 21 Mar 2019 17:08:39 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 1/2] trace: handle tracefs path truncation X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Markus Armbruster , Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" If the tracefs mountpoint has a very long path we may exceed PATH_MAX. This is a system misconfiguration and the user must resolve it so that applications can perform path-based system calls successfully. This issue does not occur on real-world systems since tracefs is mounted on /sys/kernel/debug/tracing/, but the compiler is smart enough to foresee the possibility and warn about the unchecked snprintf(3) return value. This patch fixes the compiler warning. Reported-by: Markus Armbruster Signed-off-by: Stefan Hajnoczi Reviewed-by: Liam Merwick Reviewed-by: Markus Armbruster --- trace/ftrace.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/trace/ftrace.c b/trace/ftrace.c index 61692a8682..9749543d9b 100644 --- a/trace/ftrace.c +++ b/trace/ftrace.c @@ -53,7 +53,11 @@ bool ftrace_init(void) } =20 if (tracefs_found) { - snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdir); + if (snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdi= r) + >=3D sizeof(path)) { + fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MA= X\n"); + return false; + } trace_fd =3D open(path, O_WRONLY); if (trace_fd < 0) { if (errno =3D=3D EACCES) { @@ -72,7 +76,11 @@ bool ftrace_init(void) } close(trace_fd); } - snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, subdir); + if (snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, sub= dir) + >=3D sizeof(path)) { + fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MA= X\n"); + return false; + } trace_marker_fd =3D open(path, O_WRONLY); if (trace_marker_fd < 0) { perror("Could not open ftrace 'trace_marker' file"); --=20 2.20.1