On Sep 22, 2025, at 21:20, Vaibhav Jain <jainva@google.com> wrote:
Hi Everyone,
With a1b4f28, to compute current_space, nbatch is being multiplied by BLCKSZ. nbatch is int and when multiplied with BLCKSZ, it can easily overflow the int limit.To keep the calculation safe for current_space, convert nbatch to size_t.
Please find a patch for the same.
Thanks,
Vaibhav
<0001-Fix-overflow-of-nbatch.patch>
I guess that because earlier in the function, nbatch is always clamped with:
nbatch = pg_nextpower2_32(Max(2, minbatch));
So, in practice, nbatch won’t grow to very big. But yes, if nbatch reaches to, say 1 million, it will overflow.
A simple program proves that changing nbatch to size_t will prevent from overflowing:
```
#include <stdio.h>
int main(){
size_t nbatch = 1000000; // 1 million
int BLCKSZ = 8192;
size_t result = 2 * nbatch * BLCKSZ;
printf("%zu\n", result); // will output 16384000000
return 0;
}
```
Best regards,
--
Chao Li (Evan) HighGo Software Co., Ltd. https://www.highgo.com/
