diff options
| author | Omar Sandoval <osandov@fb.com> | 2017-06-02 01:20:01 -0700 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2017-06-09 12:48:36 -0700 |
| commit | 70e7af244f24c94604ef6eca32ad297632018583 (patch) | |
| tree | 2d5fc06936f4c75b21372717a40afb4ab4c64416 | |
| parent | 452e62b71fbbefe2646fad3a968371a026936c6d (diff) | |
Btrfs: fix delalloc accounting leak caused by u32 overflow
btrfs_calc_trans_metadata_size() does an unsigned 32-bit multiplication,
which can overflow if num_items >= 4 GB / (nodesize * BTRFS_MAX_LEVEL * 2).
For a nodesize of 16kB, this overflow happens at 16k items. Usually,
num_items is a small constant passed to btrfs_start_transaction(), but
we also use btrfs_calc_trans_metadata_size() for metadata reservations
for extent items in btrfs_delalloc_{reserve,release}_metadata().
In drop_outstanding_extents(), num_items is calculated as
inode->reserved_extents - inode->outstanding_extents. The difference
between these two counters is usually small, but if many delalloc
extents are reserved and then the outstanding extents are merged in
btrfs_merge_extent_hook(), the difference can become large enough to
overflow in btrfs_calc_trans_metadata_size().
The overflow manifests itself as a leak of a multiple of 4 GB in
delalloc_block_rsv and the metadata bytes_may_use counter. This in turn
can cause early ENOSPC errors. Additionally, these WARN_ONs in
extent-tree.c will be hit when unmounting:
WARN_ON(fs_info->delalloc_block_rsv.size > 0);
WARN_ON(fs_info->delalloc_block_rsv.reserved > 0);
WARN_ON(space_info->bytes_pinned > 0 ||
space_info->bytes_reserved > 0 ||
space_info->bytes_may_use > 0);
Fix it by casting nodesize to a u64 so that
btrfs_calc_trans_metadata_size() does a full 64-bit multiplication.
While we're here, do the same in btrfs_calc_trunc_metadata_size(); this
can't overflow with any existing uses, but it's better to be safe here
than have another hard-to-debug problem later on.
Cc: stable@vger.kernel.org
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
| -rw-r--r-- | fs/btrfs/ctree.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 1e82516fe2d8..43a8c42cdf07 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -2564,7 +2564,7 @@ u64 btrfs_csum_bytes_to_leaves(struct btrfs_fs_info *fs_info, u64 csum_bytes); static inline u64 btrfs_calc_trans_metadata_size(struct btrfs_fs_info *fs_info, unsigned num_items) { - return fs_info->nodesize * BTRFS_MAX_LEVEL * 2 * num_items; + return (u64)fs_info->nodesize * BTRFS_MAX_LEVEL * 2 * num_items; } /* @@ -2574,7 +2574,7 @@ static inline u64 btrfs_calc_trans_metadata_size(struct btrfs_fs_info *fs_info, static inline u64 btrfs_calc_trunc_metadata_size(struct btrfs_fs_info *fs_info, unsigned num_items) { - return fs_info->nodesize * BTRFS_MAX_LEVEL * num_items; + return (u64)fs_info->nodesize * BTRFS_MAX_LEVEL * num_items; } int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans, |