From mboxrd@z Thu Jan 1 00:00:00 1970 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 0B645C433EF for ; Tue, 15 Feb 2022 20:19:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244060AbiBOUTn (ORCPT ); Tue, 15 Feb 2022 15:19:43 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:49054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230355AbiBOUTh (ORCPT ); Tue, 15 Feb 2022 15:19:37 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1BF8EACBD for ; Tue, 15 Feb 2022 12:19:26 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id g205-20020a2552d6000000b0061e1843b8edso41991581ybb.18 for ; Tue, 15 Feb 2022 12:19:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=3sykFJBU7TaEMZYTogVM89EYoDudBlD4QLkfsqx2ZFE=; b=QEf2mqWTjsa/E5krOX9OFf7ks4YOwL85No0GxFrV+2PebGS/cgnPqjSnvDvOSc3RvM Trxc/NaUhms8VlGKEMxWAPncnpKWXBwNLkT8jjzFbxCLXyy/RnVm2l4E4ZGu+ok0bYro KBvBrkBDZrFzWqXydq7l3gbslupJKMpdQtBTdrSzRNYfM5qOXDKhJOlSi6/37uaWqF8t TQg33AD3bLwrpN47rtY84vbuKcqHJuPVlxINx7v8M3wdXn7Vkd/yyAfLBAWG57zXkUJx z5OQ40GXQjt5ZS++yzyNLCiJFClwSux7MndH0Kvc1Ehwg7eEMR7dzBqbTgURQ84WsJwF 0MFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=3sykFJBU7TaEMZYTogVM89EYoDudBlD4QLkfsqx2ZFE=; b=zPRpMuC8ubR4UViI7UQMaiWEUtMQPcJBrHncRfcPbgBYyspfynEGFCMsWF7vNM0nKY ORU2xACbGuIu043KJz2E3z+qQ9W8N1PpY6rJYFqkGJtE1N0klUNAaZwqyQqtHXBW7c7B C+0+0gf6PJMQpM7YJsBV4bg8vwsVtCE1hPdrpriAQ4eCNEEToID0SgQtjE2QEAt20YaO bZOJt3KzVpkNPuLIMQBA+TSahlkVFrsXHU66lQnrnTySe+N6R1Eqtjny580D5nP+7WZJ jNTwWIHQ0sPtBW2URGJOEkY6WAVcPWYFRkhIsnfjR6Vom80VXZYowHNbI9f0hVn+PkaS fBxQ== X-Gm-Message-State: AOAM533drBSaqRdiChneJnj03HoyvsxO4nUlbbAmMTzJSwm9L/JLFDUF YUGYhr/EQmOtfkk2Ghyo+vYF390I964= X-Google-Smtp-Source: ABdhPJw4G1dyLTGbU/4oGbsYbMXCg+jUT4P0G7PyusNh5KoZcthlKjSwWZ7ONGwtSRvNQbayc9fkxTBjGfQ= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:c779:6798:9711:86f4]) (user=surenb job=sendgmr) by 2002:a25:dc02:: with SMTP id y2mr631611ybe.0.1644956366028; Tue, 15 Feb 2022 12:19:26 -0800 (PST) Date: Tue, 15 Feb 2022 12:19:22 -0800 Message-Id: <20220215201922.1908156-1-surenb@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.35.1.265.g69c8d7142f-goog Subject: [PATCH 1/1] mm: fix use-after-free bug when mm->mmap is reused after being freed From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: mhocko@kernel.org, mhocko@suse.com, shy828301@gmail.com, rientjes@google.com, willy@infradead.org, hannes@cmpxchg.org, guro@fb.com, riel@surriel.com, minchan@kernel.org, kirill@shutemov.name, aarcange@redhat.com, brauner@kernel.org, christian@brauner.io, hch@infradead.org, oleg@redhat.com, david@redhat.com, jannh@google.com, shakeelb@google.com, luto@kernel.org, christian.brauner@ubuntu.com, fweimer@redhat.com, jengelh@inai.de, timmurray@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com, syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After exit_mmap frees all vmas in the mm, mm->mmap needs to be reset, otherwise it points to a vma that was freed and when reused leads to a use-after-free bug. Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com Suggested-by: Michal Hocko Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/mmap.c b/mm/mmap.c index 1e8fdb0b51ed..d445c1b9d606 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3186,6 +3186,7 @@ void exit_mmap(struct mm_struct *mm) vma = remove_vma(vma); cond_resched(); } + mm->mmap = NULL; mmap_write_unlock(mm); vm_unacct_memory(nr_accounted); } -- 2.35.1.265.g69c8d7142f-goog