btrfs: avoid double put of block group when emptying cluster

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It's wrong calling btrfs_put_block_group in
__btrfs_return_cluster_to_free_space if the block group passed is
different than the block group the cluster represents. As this means the
cluster doesn't have a reference to the passed block group. This results
in double put and a use-after-free bug.

Fix this by simply bailing if the block group we passed in does not
match the block group on the cluster.

Fixes: fa9c0d795f ("Btrfs: rework allocation clustering")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

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Josef Bacik 2021-01-25 16:42:35 -05:00 • committed by David Sterba

parent 3660d0bcdb

commit 95c85fba1f

1 changed files with 4 additions and 4 deletions

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fs/btrfs/free-space-cache.c

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