21 Jun
2023
21 Jun
'23
1:29 p.m.
On Wed, 21 Jun 2023 at 08:35, Muhammad Usama Anjum usama.anjum@collabora.com wrote:
On 6/20/23 11:03 PM, Andrei Vagin wrote: ...
+struct pagemap_scan_private {
- struct page_region *vec_buf, cur_buf;
- unsigned long long vec_buf_len, vec_buf_index, max_pages, found_pages, flags;
should it be just unsigned long?
These internal values are storing data coming from user in struct pm_scan_arg in which all variables are 64 bit(__u64) explicitly. This is why we have unsigned long long here. It is absolutely necessary.
vec_buf_len and vec_buf_index can only have values in 0..512 range. flags has only a few lower bits defined (this is checked on ioctl entry) and max_pages can be limited to ULONG_MAX. Actually putting `if (!max_pages || max_pages > ULONG_MAX) max_pages = ULONG_MAX` would avoid having to check !max_pages during the walk.
Best Regards Michał Mirosław