Commit 8eb0dfdb authored May 08, 2016 by Adam Borowski Committed by David Sterba May 09, 2016

btrfs: fix int32 overflow in shrink_delalloc().



UBSAN: Undefined behaviour in fs/btrfs/extent-tree.c:4623:21
signed integer overflow:
10808 * 262144 cannot be represented in type 'int [8]'

If 8192<=items<16384, we request a writeback of an insane number of pages
which is benign (everything will be written).  But if items>=16384, the
space reservation won't be enough.

Signed-off-by: Adam Borowski <kilobyte@angband.pl>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 2f3165ec

fs/btrfs/extent-tree.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4620,7 +4620,7 @@ static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64 orig,

		/* Calc the number of the pages we need flush for space reservation */
		items = calc_reclaim_items_nr(root, to_reclaim);
		to_reclaim = items * EXTENT_SIZE_PER_ITEM;
		to_reclaim = (u64)items * EXTENT_SIZE_PER_ITEM;

		trans = (struct btrfs_trans_handle *)current->journal_info;
		block_rsv = &root->fs_info->delalloc_block_rsv;

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