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btrfs: check-integrity: Fix NULL pointer dereference for degraded mount

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[ 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 <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Qu Wenruo 2018-06-20 15:38:58 +08:00 committed by Greg Kroah-Hartman
parent 4fb2799b05
commit f88b40c147
1 changed files with 6 additions and 1 deletions
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7
fs/btrfs/check-integrity.c
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@ -1539,7 +1539,12 @@ static int btrfsic_map_block(struct btrfsic_state *state, u64 bytenr, u32 len,
}
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;