From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755270AbaDTC2I (ORCPT ); Sat, 19 Apr 2014 22:28:08 -0400 Received: from g2t2353.austin.hp.com ([15.217.128.52]:57912 "EHLO g2t2353.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755201AbaDTC0s (ORCPT ); Sat, 19 Apr 2014 22:26:48 -0400 From: Davidlohr Bueso To: akpm@linux-foundation.org Cc: zeus@gnu.org, aswin@hp.com, davidlohr@hp.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ralf Baechle , linux-mips@linux-mips.org Subject: [PATCH 3/6] mips: call find_vma with the mmap_sem held Date: Sat, 19 Apr 2014 19:26:28 -0700 Message-Id: <1397960791-16320-4-git-send-email-davidlohr@hp.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1397960791-16320-1-git-send-email-davidlohr@hp.com> References: <1397960791-16320-1-git-send-email-davidlohr@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Performing vma lookups without taking the mm->mmap_sem is asking for trouble. While doing the search, the vma in question can be modified or even removed before returning to the caller. Take the lock (exclusively) in order to avoid races while iterating through the vmacache and/or rbtree. Updates two functions: - process_fpemu_return() - cteon_flush_cache_sigtramp() This patch is completely *untested*. Signed-off-by: Davidlohr Bueso Cc: Ralf Baechle Cc: linux-mips@linux-mips.org --- arch/mips/kernel/traps.c | 2 ++ arch/mips/mm/c-octeon.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 074e857..c51bd20 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -712,10 +712,12 @@ int process_fpemu_return(int sig, void __user *fault_addr) si.si_addr = fault_addr; si.si_signo = sig; if (sig == SIGSEGV) { + down_read(¤t->mm->mmap_sem); if (find_vma(current->mm, (unsigned long)fault_addr)) si.si_code = SEGV_ACCERR; else si.si_code = SEGV_MAPERR; + up_read(¤t->mm->mmap_sem); } else { si.si_code = BUS_ADRERR; } diff --git a/arch/mips/mm/c-octeon.c b/arch/mips/mm/c-octeon.c index f41a5c5..05b1d7c 100644 --- a/arch/mips/mm/c-octeon.c +++ b/arch/mips/mm/c-octeon.c @@ -137,8 +137,10 @@ static void octeon_flush_cache_sigtramp(unsigned long addr) { struct vm_area_struct *vma; + down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, addr); octeon_flush_icache_all_cores(vma); + up_read(¤t->mm->mmap_sem); } -- 1.8.1.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f176.google.com (mail-ob0-f176.google.com [209.85.214.176]) by kanga.kvack.org (Postfix) with ESMTP id 367246B0038 for ; Sat, 19 Apr 2014 22:26:49 -0400 (EDT) Received: by mail-ob0-f176.google.com with SMTP id wp4so3064664obc.7 for ; Sat, 19 Apr 2014 19:26:49 -0700 (PDT) Received: from g2t2353.austin.hp.com (g2t2353.austin.hp.com. [15.217.128.52]) by mx.google.com with ESMTPS id jh2si26032310obb.113.2014.04.19.19.26.48 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Sat, 19 Apr 2014 19:26:48 -0700 (PDT) From: Davidlohr Bueso Subject: [PATCH 3/6] mips: call find_vma with the mmap_sem held Date: Sat, 19 Apr 2014 19:26:28 -0700 Message-Id: <1397960791-16320-4-git-send-email-davidlohr@hp.com> In-Reply-To: <1397960791-16320-1-git-send-email-davidlohr@hp.com> References: <1397960791-16320-1-git-send-email-davidlohr@hp.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: zeus@gnu.org, aswin@hp.com, davidlohr@hp.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ralf Baechle , linux-mips@linux-mips.org Performing vma lookups without taking the mm->mmap_sem is asking for trouble. While doing the search, the vma in question can be modified or even removed before returning to the caller. Take the lock (exclusively) in order to avoid races while iterating through the vmacache and/or rbtree. Updates two functions: - process_fpemu_return() - cteon_flush_cache_sigtramp() This patch is completely *untested*. Signed-off-by: Davidlohr Bueso Cc: Ralf Baechle Cc: linux-mips@linux-mips.org --- arch/mips/kernel/traps.c | 2 ++ arch/mips/mm/c-octeon.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 074e857..c51bd20 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -712,10 +712,12 @@ int process_fpemu_return(int sig, void __user *fault_addr) si.si_addr = fault_addr; si.si_signo = sig; if (sig == SIGSEGV) { + down_read(¤t->mm->mmap_sem); if (find_vma(current->mm, (unsigned long)fault_addr)) si.si_code = SEGV_ACCERR; else si.si_code = SEGV_MAPERR; + up_read(¤t->mm->mmap_sem); } else { si.si_code = BUS_ADRERR; } diff --git a/arch/mips/mm/c-octeon.c b/arch/mips/mm/c-octeon.c index f41a5c5..05b1d7c 100644 --- a/arch/mips/mm/c-octeon.c +++ b/arch/mips/mm/c-octeon.c @@ -137,8 +137,10 @@ static void octeon_flush_cache_sigtramp(unsigned long addr) { struct vm_area_struct *vma; + down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, addr); octeon_flush_icache_all_cores(vma); + up_read(¤t->mm->mmap_sem); } -- 1.8.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org