From owner-svn-src-head@freebsd.org  Tue Jan 30 23:29:27 2018
Return-Path: <owner-svn-src-head@freebsd.org>
Delivered-To: svn-src-head@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id BE8B4EC81D1;
 Tue, 30 Jan 2018 23:29:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org)
Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org
 [IPv6:2610:1c1:1:606c::19:3])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "mxrelay.nyi.freebsd.org",
 Issuer "Let's Encrypt Authority X3" (verified OK))
 by mx1.freebsd.org (Postfix) with ESMTPS id 70E5A87936;
 Tue, 30 Jan 2018 23:29:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org)
Received: from repo.freebsd.org (repo.freebsd.org
 [IPv6:2610:1c1:1:6068::e6a:0])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 678941DECA;
 Tue, 30 Jan 2018 23:29:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org)
Received: from repo.freebsd.org ([127.0.1.37])
 by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w0UNTRgU080139;
 Tue, 30 Jan 2018 23:29:27 GMT (envelope-from jhb@FreeBSD.org)
Received: (from jhb@localhost)
 by repo.freebsd.org (8.15.2/8.15.2/Submit) id w0UNTRHn080138;
 Tue, 30 Jan 2018 23:29:27 GMT (envelope-from jhb@FreeBSD.org)
Message-Id: <201801302329.w0UNTRHn080138@repo.freebsd.org>
X-Authentication-Warning: repo.freebsd.org: jhb set sender to jhb@FreeBSD.org
 using -f
From: John Baldwin <jhb@FreeBSD.org>
Date: Tue, 30 Jan 2018 23:29:27 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: svn commit: r328610 - head/sys/amd64/amd64
X-SVN-Group: head
X-SVN-Commit-Author: jhb
X-SVN-Commit-Paths: head/sys/amd64/amd64
X-SVN-Commit-Revision: 328610
X-SVN-Commit-Repository: base
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.25
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
 <svn-src-head.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head/>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 30 Jan 2018 23:29:27 -0000

Author: jhb
Date: Tue Jan 30 23:29:27 2018
New Revision: 328610
URL: https://svnweb.freebsd.org/changeset/base/328610

Log:
  Ensure 'name' is not NULL before passing to strcmp().
  
  This avoids a nested page fault when obtaining a stack trace in DDB if
  the address from the first frame does not resolve to a known symbol.
  
  MFC after:	1 week
  Sponsored by:	Chelsio Communications

Modified:
  head/sys/amd64/amd64/db_trace.c

Modified: head/sys/amd64/amd64/db_trace.c
==============================================================================
--- head/sys/amd64/amd64/db_trace.c	Tue Jan 30 23:20:41 2018	(r328609)
+++ head/sys/amd64/amd64/db_trace.c	Tue Jan 30 23:29:27 2018	(r328610)
@@ -336,7 +336,8 @@ db_backtrace(struct thread *td, struct trapframe *tf, 
 					/* Probably an assembler symbol. */
 					actframe = (void *)(tf->tf_rsp - 8);
 				}
-			} else if (strcmp(name, "fork_trampoline") == 0) {
+			} else if (name != NULL &&
+			    strcmp(name, "fork_trampoline") == 0) {
 				/*
 				 * Don't try to walk back on a stack for a
 				 * process that hasn't actually been run yet.