From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 918C56B000D for ; Tue, 17 Apr 2018 06:44:16 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id v19so11135686pfn.7 for ; Tue, 17 Apr 2018 03:44:16 -0700 (PDT) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.29.96]) by mx.google.com with ESMTPS id a15si10716405pfo.358.2018.04.17.03.44.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Apr 2018 03:44:15 -0700 (PDT) From: Chintan Pandya Subject: [PATCH v2 1/2] mm: vmalloc: Avoid racy handling of debugobjects in vunmap Date: Tue, 17 Apr 2018 16:13:47 +0530 Message-Id: <1523961828-9485-2-git-send-email-cpandya@codeaurora.org> In-Reply-To: <1523961828-9485-1-git-send-email-cpandya@codeaurora.org> References: <1523961828-9485-1-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, khandual@linux.vnet.ibm.com, mhocko@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 6729400..12d675c 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1500,7 +1500,7 @@ 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); @@ -1510,6 +1510,7 @@ 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