From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35026 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730449AbeIMTLA (ORCPT ); Thu, 13 Sep 2018 15:11:00 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qu Wenruo , David Sterba , Sasha Levin Subject: [PATCH 4.18 138/197] btrfs: check-integrity: Fix NULL pointer dereference for degraded mount Date: Thu, 13 Sep 2018 15:31:27 +0200 Message-Id: <20180913131847.077236851@linuxfoundation.org> In-Reply-To: <20180913131841.568116777@linuxfoundation.org> References: <20180913131841.568116777@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qu Wenruo [ Upstream commit 9912bbf6440ba0555e91d3306520da01872c7c1d ] Commit f8f84b2dfda5 ("btrfs: index check-integrity state hash by a dev_t") changed how btrfsic indexes device state. Now we need to access device->bdev->bd_dev, while for degraded mount it's completely possible to have device->bdev as NULL, thus it will trigger a NULL pointer dereference at mount time. Fix it by checking if the device is degraded before accessing device->bdev->bd_dev. There are a lot of other places accessing device->bdev->bd_dev, however the other call sites have either checked device->bdev, or the device->bdev is passed from btrfsic_map_block(), so it won't cause harm. Fixes: f8f84b2dfda5 ("btrfs: index check-integrity state hash by a dev_t") Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/check-integrity.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/btrfs/check-integrity.c +++ b/fs/btrfs/check-integrity.c @@ -1539,7 +1539,12 @@ static int btrfsic_map_block(struct btrf } device = multi->stripes[0].dev; - block_ctx_out->dev = btrfsic_dev_state_lookup(device->bdev->bd_dev); + if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state) || + !device->bdev || !device->name) + block_ctx_out->dev = NULL; + else + block_ctx_out->dev = btrfsic_dev_state_lookup( + device->bdev->bd_dev); block_ctx_out->dev_bytenr = multi->stripes[0].physical; block_ctx_out->start = bytenr; block_ctx_out->len = len;