Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753145AbdFGXEt (ORCPT ); Wed, 7 Jun 2017 19:04:49 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:50637 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753114AbdFGXEp (ORCPT ); Wed, 7 Jun 2017 19:04:45 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Peter Zijlstra , Alexander Shishkin , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Dmitry Vyukov , Frederic Weisbecker , Jiri Olsa , Linus Torvalds , Mathieu Desnoyers , Stephane Eranian , Thomas Gleixner , Vince Weaver , oleg@redhat.com, Ingo Molnar , Willy Tarreau Subject: [PATCH 3.10 175/250] perf/core: Fix event inheritance on fork() Date: Thu, 8 Jun 2017 00:59:21 +0200 Message-Id: <1496876436-32402-176-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1496876436-32402-1-git-send-email-w@1wt.eu> References: <1496876436-32402-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2248 Lines: 64 From: Peter Zijlstra commit e7cc4865f0f31698ef2f7aac01a50e78968985b7 upstream. While hunting for clues to a use-after-free, Oleg spotted that perf_event_init_context() can loose an error value with the result that fork() can succeed even though we did not fully inherit the perf event context. Spotted-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Dmitry Vyukov Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mathieu Desnoyers Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: oleg@redhat.com Fixes: 889ff0150661 ("perf/core: Split context's event group list into pinned and non-pinned lists") Link: http://lkml.kernel.org/r/20170316125823.190342547@infradead.org Signed-off-by: Ingo Molnar Signed-off-by: Willy Tarreau --- kernel/events/core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 76e26b8..5a550f2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7470,7 +7470,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn) ret = inherit_task_group(event, parent, parent_ctx, child, ctxn, &inherited_all); if (ret) - break; + goto out_unlock; } /* @@ -7486,7 +7486,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn) ret = inherit_task_group(event, parent, parent_ctx, child, ctxn, &inherited_all); if (ret) - break; + goto out_unlock; } raw_spin_lock_irqsave(&parent_ctx->lock, flags); @@ -7514,6 +7514,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn) } raw_spin_unlock_irqrestore(&parent_ctx->lock, flags); +out_unlock: mutex_unlock(&parent_ctx->mutex); perf_unpin_context(parent_ctx); -- 2.8.0.rc2.1.gbe9624a