On Fri, Jan 20, 2017 at 01:37:13PM -0700, Jeff Law wrote:
Which is best will depend on what the front/mid ends might have done to
apply the documented limit.
Here I know not enough to give a decision. In tree the priority_type is
unsigned short. In varasm priority is an int.
Similar functions, like arm_elf_asm_cdtor, do use the sprintf instead of
snprintf. They theoretically have the same issue.
So, either:
2.) use %.5hu in snprintf
or
3.) cast priority in snprintf to (unsigned short)
I'd go with #2. I think #3 still requires range propagation to avoid the
false positive.
I actually think 1.) is best work-around, after 18 bytes there will be some
padding so 23 bytes will almost always eat the same amount of stack space,
and we avoid actually adding some instruction to cast it or hoping all the
libcs we run on support %.5hu properly.