Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757366Ab1DHRfZ (ORCPT ); Fri, 8 Apr 2011 13:35:25 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:55671 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756547Ab1DHRfV (ORCPT ); Fri, 8 Apr 2011 13:35:21 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=jvxHZjgjqUMF8bkRSAgWFI3zRjWq1oFxl5FcTW5/0bLmP/hoXMncR2RdKFJgq9gDMs L6BCuP7hXZl8to73QKy+3OdVWBqrxF8bxkdDufM3+NOV+WHtRRAhX0u5huRGF7K8bQkc CZEHXdGvjAUCRUov+1f5mL6fYLFQJ7BhSC5xM= From: Frederic Weisbecker To: LKML Cc: LKML , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , Will Deacon , Prasad , Paul Mundt Subject: [PATCH 5/5] sh, hw_breakpoints: Fix racy access to ptrace breakpoints Date: Fri, 8 Apr 2011 19:34:27 +0200 Message-Id: <1302284067-7860-6-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <1302284067-7860-1-git-send-email-fweisbec@gmail.com> References: <1302284067-7860-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1395 Lines: 42 While the tracer accesses ptrace breakpoints, the child task may concurrently exit due to a SIGKILL and thus release its breakpoints at the same time. We can then dereference some freed pointers. To fix this, hold a reference on the child breakpoints before manipulating them. Reported-by: Oleg Nesterov Signed-off-by: Frederic Weisbecker Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Will Deacon Cc: Prasad Cc: Paul Mundt --- arch/sh/kernel/ptrace_32.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c index 2130ca6..3d7b209 100644 --- a/arch/sh/kernel/ptrace_32.c +++ b/arch/sh/kernel/ptrace_32.c @@ -117,7 +117,11 @@ void user_enable_single_step(struct task_struct *child) set_tsk_thread_flag(child, TIF_SINGLESTEP); + if (ptrace_get_breakpoints(child) < 0) + return; + set_single_step(child, pc); + ptrace_put_breakpoints(child); } void user_disable_single_step(struct task_struct *child) -- 1.7.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/