From nobody Thu Dec 18 08:37:37 2025 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 671BDECAAD5 for ; Fri, 2 Sep 2022 12:56:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238231AbiIBM4u (ORCPT ); Fri, 2 Sep 2022 08:56:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238279AbiIBMyQ (ORCPT ); Fri, 2 Sep 2022 08:54:16 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14D83F995D; Fri, 2 Sep 2022 05:38:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E41C362211; Fri, 2 Sep 2022 12:37:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C7240C433D6; Fri, 2 Sep 2022 12:37:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1662122277; bh=MSnkjPP/MYSfeJHpJPpx1Hxgi4ylFwUpQBUk8PBVVwQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HZs3ZK4tt5XHv76UEkywjCgAG4eMJHOhGGPnnpXouOkg5Uu5Oj/casmNbIuskZYM+ eR0IT0C95xkV5VmBkmNwpdpnJaOALpPGWZeT2XCP8TK+NS3ysOwQ+gbTJG+ZiWaEWQ AVPlGWAjiJqCrurmpxS6b/V8NpWw0naU/p6vYoEs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Liam R. Howlett" , syzbot+da54fa8d793ca89c741f@syzkaller.appspotmail.com, Todd Kjos , =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= , "Christian Brauner (Microsoft)" , Hridya Valsaraju , Joel Fernandes , Martijn Coenen , Suren Baghdasaryan , Andrew Morton Subject: [PATCH 5.19 69/72] android: binder: fix lockdep check on clearing vma Date: Fri, 2 Sep 2022 14:19:45 +0200 Message-Id: <20220902121407.062516874@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220902121404.772492078@linuxfoundation.org> References: <20220902121404.772492078@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Liam Howlett commit b0cab80ecd54ae3b2356bb081af0bffd538c8265 upstream. When munmapping a vma, the mmap_lock can be degraded to a write before calling close() on the file handle. The binder close() function calls binder_alloc_set_vma() to clear the vma address, which now has a lock dep check for writing on the mmap_lock. Change the lockdep check to ensure the reading lock is held while clearing and keep the write check while writing. Link: https://lkml.kernel.org/r/20220627151857.2316964-1-Liam.Howlett@oracl= e.com Fixes: 472a68df605b ("android: binder: stop saving a pointer to the VMA") Signed-off-by: Liam R. Howlett Reported-by: syzbot+da54fa8d793ca89c741f@syzkaller.appspotmail.com Acked-by: Todd Kjos Cc: "Arve Hj=C3=B8nnev=C3=A5g" Cc: Christian Brauner (Microsoft) Cc: Greg Kroah-Hartman Cc: Hridya Valsaraju Cc: Joel Fernandes Cc: Martijn Coenen Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -315,12 +315,19 @@ static inline void binder_alloc_set_vma( { unsigned long vm_start =3D 0; =20 + /* + * Allow clearing the vma with holding just the read lock to allow + * munmapping downgrade of the write lock before freeing and closing the + * file using binder_alloc_vma_close(). + */ if (vma) { vm_start =3D vma->vm_start; alloc->vma_vm_mm =3D vma->vm_mm; + mmap_assert_write_locked(alloc->vma_vm_mm); + } else { + mmap_assert_locked(alloc->vma_vm_mm); } =20 - mmap_assert_write_locked(alloc->vma_vm_mm); alloc->vma_addr =3D vm_start; } =20