From mboxrd@z Thu Jan 1 00:00:00 1970 From: tip-bot for Frederic Weisbecker Subject: [tip:perf/urgent] perf: Fix unsafe frame rewinding with hot regs fetching Date: Wed, 14 Apr 2010 06:48:06 GMT Message-ID: Reply-To: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, acme@redhat.com, paulus@samba.org, eric.dumazet@gmail.com, a.p.zijlstra@chello.nl, davem@davemloft.net, fweisbec@gmail.com, tglx@linutronix.de, linux-arch@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from hera.kernel.org ([140.211.167.34]:48364 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753365Ab0DNGsb (ORCPT ); Wed, 14 Apr 2010 02:48:31 -0400 Content-Disposition: inline Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-tip-commits@vger.kernel.org Cc: paulus@samba.org, acme@redhat.com, hpa@zytor.com, mingo@redhat.com, eric.dumazet@gmail.com, a.p.zijlstra@chello.nl, davem@davemloft.net, fweisbec@gmail.com, tglx@linutronix.de, linux-arch@vger.kernel.org Commit-ID: ab285f2b5290d92b7ec1a6f9aad54308dadf6157 Gitweb: http://git.kernel.org/tip/ab285f2b5290d92b7ec1a6f9aad54308dadf6157 Author: Frederic Weisbecker AuthorDate: Thu, 8 Apr 2010 14:05:50 +0200 Committer: Frederic Weisbecker CommitDate: Thu, 8 Apr 2010 19:03:28 +0200 perf: Fix unsafe frame rewinding with hot regs fetching When we fetch the hot regs and rewind to the nth caller, it might happen that we dereference a frame pointer outside the kernel stack boundaries, like in this example: perf_trace_sched_switch+0xd5/0x120 schedule+0x6b5/0x860 retint_careful+0xd/0x21 Since we directly dereference a userspace frame pointer here while rewinding behind retint_careful, this may end up in a crash. Fix this by simply using probe_kernel_address() when we rewind the frame pointer. This issue will have a much more proper fix in the next version of the perf_arch_fetch_caller_regs() API that will only need to rewind to the first caller. Reported-by: Eric Dumazet Signed-off-by: Frederic Weisbecker Tested-by: Eric Dumazet Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Paul Mackerras Cc: David Miller Cc: Archs --- arch/x86/kernel/dumpstack.h | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/dumpstack.h b/arch/x86/kernel/dumpstack.h index e39e771..e1a93be 100644 --- a/arch/x86/kernel/dumpstack.h +++ b/arch/x86/kernel/dumpstack.h @@ -14,6 +14,8 @@ #define get_bp(bp) asm("movq %%rbp, %0" : "=r" (bp) :) #endif +#include + extern void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, unsigned long *stack, unsigned long bp, char *log_lvl); @@ -42,8 +44,10 @@ static inline unsigned long rewind_frame_pointer(int n) get_bp(frame); #ifdef CONFIG_FRAME_POINTER - while (n--) - frame = frame->next_frame; + while (n--) { + if (probe_kernel_address(&frame->next_frame, frame)) + break; + } #endif return (unsigned long)frame;