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=-9.1 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_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 6F1A0C282CE for ; Wed, 24 Apr 2019 17:36:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 393432054F for ; Wed, 24 Apr 2019 17:36:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="gLVxWOG5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403809AbfDXRgM (ORCPT ); Wed, 24 Apr 2019 13:36:12 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:35986 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403776AbfDXRgL (ORCPT ); Wed, 24 Apr 2019 13:36:11 -0400 Received: by mail-pg1-f195.google.com with SMTP id 85so9736044pgc.3 for ; Wed, 24 Apr 2019 10:36:11 -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=b6JRiL+Dev4MgUo8nNu09/IirUrS1gRKaCe2smeftx8=; b=gLVxWOG511gTTOG0rsF0xAkktnyzBCjxI13GUziUAP4ohGVeQgauqkRV2+pJVB6djf IZqssoK6RWPs7fAViypLq+7BUrra8JQBN4o+EQo0l2PwC1ktE91PXmxpPDnm9akxtes9 Nx/W3aJ0pYRl0Sqc8ad7ZIv5yF3k0UJGz8ps0ifgeVz5ZmGFGM/3/G/7GbdSa4F8l8sF SJB+RtxneF+SUOcEl7npAR7kcnoWq+hwfBtPTiAR/Ea6Wu7kKPTR4Fz8mD8KDxpFVtgh XsPC13qUryzM9qbHGscg7pi116kP6ujzwQ4UDMxDCNoGYThujQNVWBZmKc820A/mmaIj o6eQ== 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=b6JRiL+Dev4MgUo8nNu09/IirUrS1gRKaCe2smeftx8=; b=IRgTQ4WVIMGOOmJ9QNu18BuKwYIs7gZwLf5k+722o68LCa0WCOanbptVyNfPww5XGt g6eNUV9nFcGz+pPT4k7WLMxKHyBey+kE6oDjuBsphiwsbeHN8S4ywJcZyfAqUEglLLjf Cs5O2be4jaLxyRxaZ19YjtIwiJA19VDW67TrcmudNxLFJ39hSlKLHd3fyUIrniXN0PxN ywmL0cWa+OiwG4sTsgWi8HogMe8FMDCgM/1QXjMrQkL60cVfrRwQQprIzQ4Pu6r7YBcN A6jUJKcm/QkbsJZCNW/lhpyA9TKZjRWeL0hqcAlrMf700fEXRAkYLQacEorvVpcUIQx/ qH0A== X-Gm-Message-State: APjAAAUW/O4DtXqatrPFcIONaEP5b+joW5S9BiSmb3IUeDoWHtKOyx1I Kf8GeK3b/h6ntjOUU8Vm5Y138Q== X-Google-Smtp-Source: APXvYqy68L06gV36M6EcvD1xxHurxvXlVFpKoOBMQp4jD2miyxoO6J4BGnc2MsJEOWlRtmau2As3UQ== X-Received: by 2002:a65:50c2:: with SMTP id s2mr32239343pgp.112.1556127370799; Wed, 24 Apr 2019 10:36:10 -0700 (PDT) Received: from ava-linux2.mtv.corp.google.com ([2620:0:1000:1601:6cc0:d41d:b970:fd7]) by smtp.googlemail.com with ESMTPSA id z23sm2749437pgu.32.2019.04.24.10.36.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Apr 2019 10:36:09 -0700 (PDT) From: Todd Kjos X-Google-Original-From: Todd Kjos To: tkjos@google.com, gregkh@linuxfoundation.org, arve@android.com, stable@vger.kernel.org, maco@google.com Cc: joel@joelfernandes.org, kernel-team@android.com, Todd Kjos Subject: [PATCH stable] binder: fix race between munmap() and direct reclaim Date: Wed, 24 Apr 2019 10:35:56 -0700 Message-Id: <20190424173556.85545-1-tkjos@google.com> X-Mailer: git-send-email 2.21.0.593.g511ec345e18-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 5cec2d2e5839f9c0fec319c523a911e0a7fd299f upstream. An munmap() on a binder device causes binder_vma_close() to be called which clears the alloc->vma pointer. If direct reclaim causes binder_alloc_free_page() to be called, there is a race where alloc->vma is read into a local vma pointer and then used later after the mm->mmap_sem is acquired. This can result in calling zap_page_range() with an invalid vma which manifests as a use-after-free in zap_page_range(). The fix is to check alloc->vma after acquiring the mmap_sem (which we were acquiring anyway) and skip zap_page_range() if it has changed to NULL. Signed-off-by: Todd Kjos Reviewed-by: Joel Fernandes (Google) Cc: stable # 5.0, 4.19, 4.14 Signed-off-by: Greg Kroah-Hartman --- Greg: This applies to 5.0, 4.19, 4.14. Not needed before 4.12. drivers/android/binder_alloc.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index 022cd80e80cc..a6e556bf62df 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -959,14 +959,13 @@ enum lru_status binder_alloc_free_page(struct list_head *item, index = page - alloc->pages; page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE; + + mm = alloc->vma_vm_mm; + if (!mmget_not_zero(mm)) + goto err_mmget; + if (!down_write_trylock(&mm->mmap_sem)) + goto err_down_write_mmap_sem_failed; vma = binder_alloc_get_vma(alloc); - if (vma) { - if (!mmget_not_zero(alloc->vma_vm_mm)) - goto err_mmget; - mm = alloc->vma_vm_mm; - if (!down_write_trylock(&mm->mmap_sem)) - goto err_down_write_mmap_sem_failed; - } list_lru_isolate(lru, item); spin_unlock(lock); @@ -979,10 +978,9 @@ enum lru_status binder_alloc_free_page(struct list_head *item, PAGE_SIZE); trace_binder_unmap_user_end(alloc, index); - - up_write(&mm->mmap_sem); - mmput(mm); } + up_write(&mm->mmap_sem); + mmput(mm); trace_binder_unmap_kernel_start(alloc, index); -- 2.21.0.392.gf8f6787159e-goog