From nobody Wed Apr 8 17:30:14 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2E6BC38A02 for ; Fri, 28 Oct 2022 06:51:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229981AbiJ1Gv1 (ORCPT ); Fri, 28 Oct 2022 02:51:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229946AbiJ1GvG (ORCPT ); Fri, 28 Oct 2022 02:51:06 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06BF81A1 for ; Thu, 27 Oct 2022 23:48:39 -0700 (PDT) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MzCj13RstzpWHq; Fri, 28 Oct 2022 14:45:09 +0800 (CST) Received: from huawei.com (10.67.175.21) by kwepemi500012.china.huawei.com (7.221.188.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 28 Oct 2022 14:48:36 +0800 From: Li Zetao To: CC: , , , , , , , Subject: [PATCH v2] mm/mmap: Fix memory leak in mmap_region() Date: Fri, 28 Oct 2022 15:37:17 +0800 Message-ID: <20221028073717.1179380-1-lizetao1@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221027073029.dyo2p2kearlutizq@revolver> References: <20221027073029.dyo2p2kearlutizq@revolver> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.67.175.21] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemi500012.china.huawei.com (7.221.188.12) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" There is a memory leak reported by kmemleak: unreferenced object 0xffff88817231ce40 (size 224): comm "mount.cifs", pid 19308, jiffies 4295917571 (age 405.880s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 60 c0 b2 00 81 88 ff ff 98 83 01 42 81 88 ff ff `..........B.... backtrace: [] __alloc_file+0x21/0x250 [] alloc_empty_file+0x41/0xf0 [] alloc_file+0x59/0x710 [] alloc_file_pseudo+0x154/0x210 [] __shmem_file_setup+0xff/0x2a0 [] shmem_zero_setup+0x8d/0x160 [] mmap_region+0x1075/0x19d0 [] do_mmap+0x727/0x1110 [] vm_mmap_pgoff+0x112/0x1e0 [] do_syscall_64+0x35/0x80 [] entry_SYSCALL_64_after_hwframe+0x46/0xb0 The root cause was traced to an error handing path in mmap_region() when arch_validate_flags() or mas_preallocate() fails. In the shared anonymous mapping sence, vma will be setuped and mapped with a new shared anonymous file via shmem_zero_setup(). So in this case, the file resource needs to be released. Fix it by calling fput(vma->vm_file) and unmap_region() when arch_validate_flags() or mas_preallocate() returns an error in the shared anonymous mapping sence. Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") Fixes: c462ac288f2c ("mm: Introduce arch_validate_flags()") Signed-off-by: Li Zetao Reviewed-by: Liam R. Howlett --- v1 was posted at: https://lore.kernel.org/all/20221027025837.136492-1-lizet= ao1@huawei.com/ v1 -> v2: Drop the new goto label, and jump to unmap_and_free_vma "if (vma-= >vm_file)" mm/mmap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index e270057ed04e..77846d8cf9d4 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2674,6 +2674,8 @@ unsigned long mmap_region(struct file *file, unsigned= long addr, error =3D -EINVAL; if (file) goto close_and_free_vma; + else if (vma->vm_file) + goto unmap_and_free_vma; else goto free_vma; } @@ -2682,6 +2684,8 @@ unsigned long mmap_region(struct file *file, unsigned= long addr, error =3D -ENOMEM; if (file) goto close_and_free_vma; + else if (vma->vm_file) + goto unmap_and_free_vma; else goto free_vma; } @@ -2751,7 +2755,7 @@ unsigned long mmap_region(struct file *file, unsigned= long addr, =20 /* Undo any partial mapping done by a device driver. */ unmap_region(mm, mas.tree, vma, prev, next, vma->vm_start, vma->vm_end); - if (vm_flags & VM_SHARED) + if (file && (vm_flags & VM_SHARED)) mapping_unmap_writable(file->f_mapping); free_vma: vm_area_free(vma); --=20 2.25.1