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 X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B40FC433FF for ; Mon, 29 Jul 2019 22:16:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D3ED2073F for ; Mon, 29 Jul 2019 22:16:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="YB4YUwXy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728089AbfG2WQU (ORCPT ); Mon, 29 Jul 2019 18:16:20 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:46063 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726327AbfG2WQU (ORCPT ); Mon, 29 Jul 2019 18:16:20 -0400 Received: by mail-pg1-f195.google.com with SMTP id o13so28921962pgp.12 for ; Mon, 29 Jul 2019 15:16:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=BYK7OhY4Zs3xEZ3rD2sAHSi4xgYu3lqni8LNbwDhtKA=; b=YB4YUwXyAaJ50+M7syE0Q4lgd+aJqSKTnUaCXTYF6UidYNiOj8TLOqoPs6e3uO3YjI jFeoBQHavH7cJ2LgKOCwQNWhQ5oWgr9maUjmmb+CpN87lkLGpilBgKEv5iJzO8Fipjj1 VPOCfP3g77t8ByA+fjKHyIbXvppVz7jlDhfkeAzm/LFBIa8/5j6sKKC2zojf/Ox8/cUQ QpHQlvRWzT4WOcze51+tohdzGCOR0MRdJ5tCWXD1ijCc5pzwDiQ3JbXS5p4LKaB1qq53 xJsKhu7sLNkr0PIxbZJp55sEnuaabVHtmHMYPZLHlqBd5rxOuWwPKcBuNH4UN3p1zCAA Tw/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=BYK7OhY4Zs3xEZ3rD2sAHSi4xgYu3lqni8LNbwDhtKA=; b=lmMmoPyRz4B5pKuR50jVHsQq5FY7RLzVzL0gCzFmXWT4UuuwodNUzOpqWY+2muaed6 Zn9qXlQvPZsIlUMs7AWDYMbqeLCfPXK+0N/kamYmzErI5WdATwPcaQaAzayrqUPiul3i GwKpRQn2uee2kPpvgN4VEE2Btv7c+41+2ucdygShf70VlfwthtUKCXIp8m2+uSGvkkNE sQw3kRDla4Mw0oefGAUfxVz57iw9xabawK7FBem3tJuQo1WpvdS7VEUxQzvfV6bmHccE MFilws8/Glw+wzrn7Q5LzIgvwHrWlmlaw1o1DD5NeNgVVqDrdns4fT6uNy8l0TX/7JeH KauQ== X-Gm-Message-State: APjAAAU8SxiJW9Lkg1OF2ieZA90mRie+2JZgk5dUcGNv9Y6Qv+OWO4ws nWi/JA5eqOSq+mknUK9qY6k= X-Google-Smtp-Source: APXvYqxFy/r3gUtE9Br/3RiI2lkMxMaKMK/cS/GEPfggKg1YrnVSQ12+QnRB5DJbaJXjUBemSY3uow== X-Received: by 2002:a17:90a:35e6:: with SMTP id r93mr114645865pjb.20.1564438579714; Mon, 29 Jul 2019 15:16:19 -0700 (PDT) Received: from ava-linux2.mtv.corp.google.com ([2620:15c:211:0:b2de:593e:a6f0:9b20]) by smtp.googlemail.com with ESMTPSA id o3sm116637836pje.1.2019.07.29.15.16.18 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 29 Jul 2019 15:16:18 -0700 (PDT) From: Todd Kjos X-Google-Original-From: Todd Kjos To: tkjos@google.com, gregkh@linuxfoundation.org, arve@android.com, maco@google.com, stable@vger.kernel.org Cc: joel@joelfernandes.org, kernel-team@android.com, Todd Kjos Subject: [PATCH 4.14,4.19] binder: fix possible UAF when freeing buffer Date: Mon, 29 Jul 2019 15:16:06 -0700 Message-Id: <20190729221606.243098-1-tkjos@google.com> X-Mailer: git-send-email 2.22.0.709.g102302147b-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Todd Kjos commit a370003cc301d4361bae20c9ef615f89bf8d1e8a upstream There is a race between the binder driver cleaning up a completed transaction via binder_free_transaction() and a user calling binder_ioctl(BC_FREE_BUFFER) to release a buffer. It doesn't matter which is first but they need to be protected against running concurrently which can result in a UAF. Signed-off-by: Todd Kjos Cc: stable # 4.14 4.19 Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 5d67f5fec6c1b..2decb1a5a8e2f 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1960,8 +1960,18 @@ static struct binder_thread *binder_get_txn_from_and_acq_inner( static void binder_free_transaction(struct binder_transaction *t) { - if (t->buffer) - t->buffer->transaction = NULL; + struct binder_proc *target_proc = t->to_proc; + + if (target_proc) { + binder_inner_proc_lock(target_proc); + if (t->buffer) + t->buffer->transaction = NULL; + binder_inner_proc_unlock(target_proc); + } + /* + * If the transaction has no target_proc, then + * t->buffer->transaction has already been cleared. + */ kfree(t); binder_stats_deleted(BINDER_STAT_TRANSACTION); } @@ -3484,10 +3494,12 @@ static int binder_thread_write(struct binder_proc *proc, buffer->debug_id, buffer->transaction ? "active" : "finished"); + binder_inner_proc_lock(proc); if (buffer->transaction) { buffer->transaction->buffer = NULL; buffer->transaction = NULL; } + binder_inner_proc_unlock(proc); if (buffer->async_transaction && buffer->target_node) { struct binder_node *buf_node; struct binder_work *w; -- 2.22.0.709.g102302147b-goog