From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934878AbeBMLl2 (ORCPT ); Tue, 13 Feb 2018 06:41:28 -0500 Received: from terminus.zytor.com ([198.137.202.136]:58465 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934086AbeBMLl0 (ORCPT ); Tue, 13 Feb 2018 06:41:26 -0500 Date: Tue, 13 Feb 2018 03:29:46 -0800 From: tip-bot for Josh Poimboeuf Message-ID: Cc: brgerst@gmail.com, tglx@linutronix.de, bp@alien8.de, torvalds@linux-foundation.org, jpoimboe@redhat.com, luto@kernel.org, arjan@linux.intel.com, fengguang.wu@intel.com, peterz@infradead.org, mingo@kernel.org, hpa@zytor.com, dvlasenk@redhat.com, linux-kernel@vger.kernel.org Reply-To: linux-kernel@vger.kernel.org, dvlasenk@redhat.com, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, fengguang.wu@intel.com, arjan@linux.intel.com, luto@kernel.org, torvalds@linux-foundation.org, jpoimboe@redhat.com, bp@alien8.de, tglx@linutronix.de, brgerst@gmail.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/pti] objtool: Fix segfault in ignore_unreachable_insn() Git-Commit-ID: 59d13cd6789e8feb4615bb999d46bbd439a9a396 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 59d13cd6789e8feb4615bb999d46bbd439a9a396 Gitweb: https://git.kernel.org/tip/59d13cd6789e8feb4615bb999d46bbd439a9a396 Author: Josh Poimboeuf AuthorDate: Thu, 8 Feb 2018 17:09:25 -0600 Committer: Ingo Molnar CommitDate: Tue, 13 Feb 2018 11:46:59 +0100 objtool: Fix segfault in ignore_unreachable_insn() Peter Zijlstra's patch for converting WARN() to use UD2 triggered a bunch of false "unreachable instruction" warnings, which then triggered a seg fault in ignore_unreachable_insn(). The seg fault happened when it tried to dereference a NULL 'insn->func' pointer. Thanks to static_cpu_has(), some functions can jump to a non-function area in the .altinstr_aux section. That breaks ignore_unreachable_insn()'s assumption that it's always inside the original function. Make sure ignore_unreachable_insn() only follows jumps within the current function. Reported-by: Borislav Petkov Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: kbuild test robot Link: http://lkml.kernel.org/r/bace77a60d5af9b45eddb8f8fb9c776c8de657ef.1518130694.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- tools/objtool/check.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 2e458eb..c7fb5c2 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1935,13 +1935,19 @@ static bool ignore_unreachable_insn(struct instruction *insn) if (is_kasan_insn(insn) || is_ubsan_insn(insn)) return true; - if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest) { - insn = insn->jump_dest; - continue; + if (insn->type == INSN_JUMP_UNCONDITIONAL) { + if (insn->jump_dest && + insn->jump_dest->func == insn->func) { + insn = insn->jump_dest; + continue; + } + + break; } if (insn->offset + insn->len >= insn->func->offset + insn->func->len) break; + insn = list_next_entry(insn, list); }