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 <[email protected]> Reviewed-by: David Sterba <[email protected]> Signed-off-by: David Sterba <[email protected]>
kyagi · May 9, 2016 · 8eb0dfd · 8eb0dfd
1 parent 2f3165e
commit 8eb0dfd
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
@@ -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;