On Wed, 14 Mar 2018 22:36:21 +0300 Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> Hello Andrew Morton,
>
> The patch f79e2abb9bd4: "[PATCH] sys_sync_file_range()" from Mar 31,
> 2006, leads to the following static checker warning:
>
> fs/sync.c:298 ksys_sync_file_range()
> warn: signed overflow undefined. 'offset + nbytes < offset'
>
> fs/sync.c
> 279 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
> 280 unsigned int flags)
> 281 {
> 282 int ret;
> 283 struct fd f;
> 284 struct address_space *mapping;
> 285 loff_t endbyte; /* inclusive */
> 286 umode_t i_mode;
> 287
> 288 ret = -EINVAL;
> 289 if (flags & ~VALID_FLAGS)
> 290 goto out;
> 291
> 292 endbyte = offset + nbytes;
> 293
> 294 if ((s64)offset < 0)
> 295 goto out;
> 296 if ((s64)endbyte < 0)
> 297 goto out;
> 298 if (endbyte < offset)
> ^^^^^^^^^^^^^^^^
> This is undefined but I think it works with the kernel build options?
>
Yup. -fno-strict-overflow. Please see Dmitry's explanation at
https://bugzilla.kernel.org/show_bug.cgi?id=199099.
