Alloc memory with custom protection.

[stiff eagle]

I'm working at windows 11 and i need to alloc memory for shellcode (raw function bytes).
Is there way to alloc memory using some of zig builtin allocators with execution allowance by default? Like for example here:

void* exec = VirtualAlloc(NULL, sizeof(sc), MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);

Where PAGE_EXECUTE_READWRITE means that memory region can be executed as code.

[restive kettle]

that wouldnt really make sense since the allocator api rarely corresponds to actual pages, they sometimes dont even correspond to stuff on the heap
like how would an arena allocator do this? or especially a fixed buffer allocator
you should probably use std.posix.mmap directly

[iron gazelle]

The only allocator it would make sense for is std.heap.PageAllocator, and even then I think making executable the default is a security footgun.

[desert radish]

use any allocator to alloc an std.mem.page_size aligned slice of u8 where the length is also aligned
use whatever function to make it executable (and probably read-only too)
then make it non executable and writable before you free it, because freeing will write to it in safe builds

[echo nebula]

it doesn't seem like you can do this using the builtin allocators, but you are always welcome to write a custom allocator by returning some function pointers

[desert radish]

you could probably just make an allocator that wraps any other allocator and changes the permissions on the memory

well

you'd need to always allocate page-aligned memory from the underlying allocator even when the request to this custom allocator isn't aligned

[stiff eagle]

Looks like the best way to achieve what i need will be is to use VirtualProtect WInAPI function with usage of page_allocator