From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f169.google.com (mail-pd0-f169.google.com [209.85.192.169]) by kanga.kvack.org (Postfix) with ESMTP id 09B7A6B0039 for ; Sat, 19 Apr 2014 22:26:49 -0400 (EDT) Received: by mail-pd0-f169.google.com with SMTP id fp1so2583397pdb.14 for ; Sat, 19 Apr 2014 19:26:49 -0700 (PDT) Received: from g2t2354.austin.hp.com (g2t2354.austin.hp.com. [15.217.128.53]) by mx.google.com with ESMTPS id fn10si17741621pad.156.2014.04.19.19.26.48 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Sat, 19 Apr 2014 19:26:49 -0700 (PDT) From: Davidlohr Bueso Subject: [PATCH 2/6] m68k: call find_vma with the mmap_sem held in sys_cacheflush() Date: Sat, 19 Apr 2014 19:26:27 -0700 Message-Id: <1397960791-16320-3-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, Geert Uytterhoeven , linux-m68k@lists.linux-m68k.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 (shared) in order to avoid races while iterating through the vmacache and/or rbtree. This patch is completely *untested*. Signed-off-by: Davidlohr Bueso Cc: Geert Uytterhoeven Cc: linux-m68k@lists.linux-m68k.org --- arch/m68k/kernel/sys_m68k.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/arch/m68k/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c index 3a480b3..d2263a0 100644 --- a/arch/m68k/kernel/sys_m68k.c +++ b/arch/m68k/kernel/sys_m68k.c @@ -376,7 +376,6 @@ cache_flush_060 (unsigned long addr, int scope, int cache, unsigned long len) asmlinkage int sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len) { - struct vm_area_struct *vma; int ret = -EINVAL; if (scope < FLUSH_SCOPE_LINE || scope > FLUSH_SCOPE_ALL || @@ -389,16 +388,23 @@ sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len) if (!capable(CAP_SYS_ADMIN)) goto out; } else { + struct vm_area_struct *vma; + bool invalid; + + /* Check for overflow. */ + if (addr + len < addr) + goto out; + /* * Verify that the specified address region actually belongs * to this process. */ - vma = find_vma (current->mm, addr); ret = -EINVAL; - /* Check for overflow. */ - if (addr + len < addr) - goto out; - if (vma == NULL || addr < vma->vm_start || addr + len > vma->vm_end) + down_read(¤t->mm->mmap_sem); + vma = find_vma(current->mm, addr); + invalid = !vma || addr < vma->vm_start || addr + len > vma->vm_end; + up_read(¤t->mm->mmap_sem); + if (invalid) goto out; } -- 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