Coverity scan for 5.5.0-rc4 found a possible integer overflow in
tree-checker.c line 364.
`prev_csum_end = (prev_item_size / csumsize) * sectorsize;`
Quoting from scan results:
```
CID 1456959 Unintentional integer overflow
Unintentional integer overflow (OVERFLOW_BEFORE_WIDEN) overflow_before_widen:
Potentially overflowing expression `prev_item_size / csumsize * sectorsize`
with type unsigned int (32 bits, unsigned) is evaluated using 32-bit
arithmetic, and then used in a context that expects an expression of type u64.
(64 bits, unsigned).
```
Added a cast to `u64` on the left hand side of the expression.
Compiles fine on x86_64_defconfig with all btrfs config flags enabled.
Signed-off-by: Cengiz Can <cengiz@xxxxxxxxxx>
---
fs/btrfs/tree-checker.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 97f3520b8d98..9f58f07be779 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -361,7 +361,7 @@ static int check_csum_item(struct extent_buffer *leaf, struct btrfs_key *key,
u32 prev_item_size;
prev_item_size = btrfs_item_size_nr(leaf, slot - 1);
- prev_csum_end = (prev_item_size / csumsize) * sectorsize;
+ prev_csum_end = (u64) (prev_item_size / csumsize) * sectorsize;
prev_csum_end += prev_key->offset;
if (prev_csum_end > key->offset) {
generic_err(leaf, slot - 1,
--
2.20.1
