From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751925AbZHJSCJ (ORCPT ); Mon, 10 Aug 2009 14:02:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751804AbZHJSCH (ORCPT ); Mon, 10 Aug 2009 14:02:07 -0400 Received: from hera.kernel.org ([140.211.167.34]:46188 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751543AbZHJSCG (ORCPT ); Mon, 10 Aug 2009 14:02:06 -0400 Date: Mon, 10 Aug 2009 18:01:24 GMT From: tip-bot for Frederic Weisbecker To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, acme@redhat.com, hpa@zytor.com, mingo@redhat.com, efault@gmx.de, peterz@infradead.org, fweisbec@gmail.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, acme@redhat.com, linux-kernel@vger.kernel.org, fweisbec@gmail.com, peterz@infradead.org, efault@gmx.de, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1249915116-5210-1-git-send-email-fweisbec@gmail.com> References: <1249915116-5210-1-git-send-email-fweisbec@gmail.com> Subject: [tip:perfcounters/urgent] perf_counter: Zero dead bytes from ftrace raw samples size alignment Message-ID: Git-Commit-ID: 1853db0e02ae4088f102b0d8e59e83dc98f93f03 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Mon, 10 Aug 2009 18:01:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 1853db0e02ae4088f102b0d8e59e83dc98f93f03 Gitweb: http://git.kernel.org/tip/1853db0e02ae4088f102b0d8e59e83dc98f93f03 Author: Frederic Weisbecker AuthorDate: Mon, 10 Aug 2009 16:38:36 +0200 Committer: Ingo Molnar CommitDate: Mon, 10 Aug 2009 16:51:19 +0200 perf_counter: Zero dead bytes from ftrace raw samples size alignment After aligning the ftrace raw samples, there are dead bytes storing random data from the stack. We don't want to leak these to userspace, then zero these out. Before: 0x2de88 [0x50]: event: 9 . . ... raw event: size 80 bytes . 0000: 09 00 00 00 01 00 50 00 d0 c7 00 81 ff ff ff ff ......P........ . 0010: 68 01 00 00 68 01 00 00 2c 00 00 00 00 00 00 00 h...h...,...... . 0020: 2c 00 00 00 2b 00 01 02 68 01 00 00 68 01 00 00 ,...+...h...h.. . 0030: 6b 6f 6e 64 65 6d 61 6e 64 2f 30 00 00 00 00 00 kondemand/0.... . 0040: 68 01 00 00 40 7f 46 81 ff ff ff ff 00 10 1b 7f h...@.F........ ^ ^ ^ ^ Leak After: 0x2d318 [0x50]: event: 9 . . ... raw event: size 80 bytes . 0000: 09 00 00 00 01 00 50 00 d0 c7 00 81 ff ff ff ff ......P........ . 0010: 68 01 00 00 68 01 00 00 68 14 00 00 00 00 00 00 h...h...h...... . 0020: 2c 00 00 00 2b 00 01 02 68 01 00 00 68 01 00 00 ,...+...h...h.. . 0030: 6b 6f 6e 64 65 6d 61 6e 64 2f 30 00 00 00 00 00 kondemand/0.... . 0040: 68 01 00 00 a0 80 46 81 ff ff ff ff 00 00 00 00 h.....F........ ^ ^ ^ ^ Fixed Reported-by: Peter Zijlstra Signed-off-by: Frederic Weisbecker Cc: Frederic Weisbecker Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Mike Galbraith LKML-Reference: <1249915116-5210-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Mike Galbraith --- include/trace/ftrace.h | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index a05524f..f64fbaa 100644 --- a/include/trace/ftrace.h +++ b/include/trace/ftrace.h @@ -648,6 +648,9 @@ __attribute__((section("_ftrace_events"))) event_##call = { \ * char raw_data[__entry_size]; <- allocate our sample in the stack * struct trace_entry *ent; * + * zero dead bytes from alignment to avoid stack leak to userspace: + * + * *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; * entry = (struct ftrace_raw_ *)raw_data; * ent = &entry->ent; * tracing_generic_entry_update(ent, irq_flags, pc); @@ -698,6 +701,7 @@ static void ftrace_profile_##call(proto) \ char raw_data[__entry_size]; \ struct trace_entry *ent; \ \ + *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \ entry = (struct ftrace_raw_##call *)raw_data; \ ent = &entry->ent; \ tracing_generic_entry_update(ent, irq_flags, pc); \