Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755255AbaDTC1t (ORCPT ); Sat, 19 Apr 2014 22:27:49 -0400 Received: from g2t2353.austin.hp.com ([15.217.128.52]:57905 "EHLO g2t2353.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755187AbaDTC0p (ORCPT ); Sat, 19 Apr 2014 22:26:45 -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, Steven Miao , adi-buildroot-devel@lists.sourceforge.net Subject: [PATCH 1/6] blackfin/ptrace: call find_vma with the mmap_sem held Date: Sat, 19 Apr 2014 19:26:26 -0700 Message-Id: <1397960791-16320-2-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 (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: Steven Miao Cc: adi-buildroot-devel@lists.sourceforge.net --- arch/blackfin/kernel/ptrace.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/blackfin/kernel/ptrace.c b/arch/blackfin/kernel/ptrace.c index e1f88e0..8b8fe67 100644 --- a/arch/blackfin/kernel/ptrace.c +++ b/arch/blackfin/kernel/ptrace.c @@ -117,6 +117,7 @@ put_reg(struct task_struct *task, unsigned long regno, unsigned long data) int is_user_addr_valid(struct task_struct *child, unsigned long start, unsigned long len) { + bool valid; struct vm_area_struct *vma; struct sram_list_struct *sraml; @@ -124,9 +125,12 @@ is_user_addr_valid(struct task_struct *child, unsigned long start, unsigned long if (start + len < start) return -EIO; + down_read(&child->mm->mmap_sem); vma = find_vma(child->mm, start); - if (vma && start >= vma->vm_start && start + len <= vma->vm_end) - return 0; + valid = vma && start >= vma->vm_start && start + len <= vma->vm_end; + up_read(&child->mm->mmap_sem); + if (valid) + return 0; for (sraml = child->mm->context.sram_list; sraml; sraml = sraml->next) if (start >= (unsigned long)sraml->addr -- 1.8.1.4 -- 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/