btrfs: fix use after free iterating extrefs
The code for btrfs inode-resolve has never worked properly for files with enough hard links to trigger extrefs. It was trying to get the leaf out of a path after freeing the path: btrfs_release_path(path); leaf = path->nodes[0]; item_size = btrfs_item_size_nr(leaf, slot); The fix here is to use the extent buffer we cloned just a little higher up to avoid deadlocks caused by using the leaf in the path. Signed-off-by: Chris Mason <clm@fb.com> cc: stable@vger.kernel.org # v3.7+ cc: Mark Fasheh <mfasheh@suse.de> Reviewed-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Mark Fasheh <mfasheh@suse.de> Signed-off-by: Chris Mason <clm@fb.com>
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@ -1834,7 +1834,6 @@ static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
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int found = 0;
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struct extent_buffer *eb;
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struct btrfs_inode_extref *extref;
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struct extent_buffer *leaf;
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u32 item_size;
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u32 cur_offset;
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unsigned long ptr;
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@ -1862,9 +1861,8 @@ static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
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btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
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btrfs_release_path(path);
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leaf = path->nodes[0];
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item_size = btrfs_item_size_nr(leaf, slot);
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ptr = btrfs_item_ptr_offset(leaf, slot);
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item_size = btrfs_item_size_nr(eb, slot);
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ptr = btrfs_item_ptr_offset(eb, slot);
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cur_offset = 0;
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while (cur_offset < item_size) {
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@ -1878,7 +1876,7 @@ static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
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if (ret)
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break;
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cur_offset += btrfs_inode_extref_name_len(leaf, extref);
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cur_offset += btrfs_inode_extref_name_len(eb, extref);
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cur_offset += sizeof(*extref);
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}
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btrfs_tree_read_unlock_blocking(eb);
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