Commit f8f84b2dfda5 ("btrfs: index check-integrity state hash by a dev_t")
changed how btrfsic how we index device state hash.
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 <w...@suse.com>
---
Please note there are still quite some problem about check-integrity,
including:
1) Warning for degraded mount
2) Meaningless empty lines output
This patch will only fix the obvious NULL pointer dereference exposed by
btrfs/027 with "check_int" mount option.
---
fs/btrfs/check-integrity.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index a3fdb4fe967d..daf45472bef9 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -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;
--
2.17.1
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