From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f72.google.com (mail-pl0-f72.google.com [209.85.160.72]) by kanga.kvack.org (Postfix) with ESMTP id 067AA6B000C for ; Fri, 13 Apr 2018 07:34:16 -0400 (EDT) Received: by mail-pl0-f72.google.com with SMTP id y7-v6so5761474plh.7 for ; Fri, 13 Apr 2018 04:34:15 -0700 (PDT) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.29.96]) by mx.google.com with ESMTPS id d13si3851790pgn.334.2018.04.13.04.34.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 13 Apr 2018 04:34:14 -0700 (PDT) From: Chintan Pandya Subject: [PATCH 1/2] mm: vmalloc: Avoid racy handling of debugobjects in vunmap Date: Fri, 13 Apr 2018 17:03:53 +0530 Message-Id: <1523619234-17635-2-git-send-email-cpandya@codeaurora.org> In-Reply-To: <1523619234-17635-1-git-send-email-cpandya@codeaurora.org> References: <1523619234-17635-1-git-send-email-cpandya@codeaurora.org> Sender: owner-linux-mm@kvack.org List-ID: To: vbabka@suse.cz, labbott@redhat.com, catalin.marinas@arm.com, hannes@cmpxchg.org, f.fainelli@gmail.com, xieyisheng1@huawei.com, ard.biesheuvel@linaro.org, richard.weiyang@gmail.com, byungchul.park@lge.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chintan Pandya Currently, __vunmap flow is, 1) Release the VM area 2) Free the debug objects corresponding to that vm area. This leave some race window open. 1) Release the VM area 1.5) Some other client gets the same vm area 1.6) This client allocates new debug objects on the same vm area 2) Free the debug objects corresponding to this vm area. Here, we actually free 'other' client's debug objects. Fix this by freeing the debug objects first and then releasing the VM area. Signed-off-by: Chintan Pandya --- mm/vmalloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ebff729..9ff21a1 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1519,7 +1519,7 @@ static void __vunmap(const void *addr, int deallocate_pages) addr)) return; - area = remove_vm_area(addr); + area = find_vmap_area((unsigned long)addr)->vm; if (unlikely(!area)) { WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n", addr); @@ -1529,6 +1529,7 @@ static void __vunmap(const void *addr, int deallocate_pages) debug_check_no_locks_freed(addr, get_vm_area_size(area)); debug_check_no_obj_freed(addr, get_vm_area_size(area)); + remove_vm_area(addr); if (deallocate_pages) { int i; -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative Project