subhook_make_jmp64 might SIGSEGV if a function is located across a page boundary about subhook HOT 3 OPEN

I also came across this issue today. In Swarm64 (https://swarm64.com/) we are using the subhook library, and got seg fault because of a page boundary issue. Applying the fix that @cube0x8 (big acknowledgements btw) proposed solved the problem.

from subhook.

I'm pretty sure this is an issue with mprotect
Using the code you posted still shows the permissions shared over 0x1000 bytes

from subhook.

Sorry, but I don't get your point. Which code are you talking about?

I guess I was not clear enough in my first comment, so let me try to explain it better:

As you said, the permissions are shared over 0x1000 bytes which is right, but the problem arises when a function is located at page boundary.

Let's take your screenshot as example:
e.g. we have a function which is located at 0x7faff2692fef. mprotect (which takes a page aligned address as argument, otherwise it fails) will change permission as RWX from 0x7faff2692000 to 0x7faff2693000 (as showed in the picture). But later on, subhook will try to patch the first 0x14 bytes of the function, which are located in memory from 0x7faff2692fef to 0x7faff2693003. Conclusion: we have exactly 0x3 bytes which are not subjected to the mprotect changes, which eventually will lead to a SIGSEGV.

from subhook.