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fix(dl-tls): TLS overallocation

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* `offset` is the offset in TLS to copy initial data to NOT the segment
  size
* Only zero the region which is required to be zeroed

Signed-off-by: Anhad Singh <andypython@protonmail.com>
This commit is contained in:
Anhad Singh
2025-12-29 17:08:33 +11:00
parent be446db7c3
commit 75f6b9d64e
4 changed files with 32 additions and 19 deletions
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src/header/dl-tls/mod.rs
+20 -11
View File
@@ -1,14 +1,17 @@
//! dl-tls implementation for Redox
#![deny(unsafe_op_in_unsafe_fn)]
// FIXME(andypython): remove this when #![allow(warnings, unused_variables)] is
// dropped from src/lib.rs.
#![warn(warnings, unused_variables)]
use core::{alloc::Layout, arch::global_asm};
use alloc::alloc::alloc_zeroed;
use alloc::alloc::alloc;
use core::{alloc::Layout, ptr};
use crate::{ld_so::tcb::Tcb, platform::types::*};
#[repr(C)]
#[allow(non_camel_case_types)]
pub struct dl_tls_index {
pub ti_module: usize,
pub ti_offset: usize,
@@ -18,7 +21,7 @@ pub struct dl_tls_index {
pub unsafe extern "C" fn __tls_get_addr(ti: *mut dl_tls_index) -> *mut c_void {
let tcb = unsafe { Tcb::current().unwrap() };
let ti = unsafe { &*ti };
let masters = unsafe { tcb.masters().unwrap() };
let masters = tcb.masters().unwrap();
trace!(
"__tls_get_addr({:p}: {:#x}, {:#x}, masters_len={}, dtv_len={})",
@@ -40,15 +43,21 @@ pub unsafe extern "C" fn __tls_get_addr(ti: *mut dl_tls_index) -> *mut c_void {
// Allocate TLS for module.
let master = &masters[dtv_index];
// FIXME(andypython): master.align
let layout = unsafe {
Layout::from_size_align_unchecked(master.offset /* aligned ph.p_memsz */, 16)
let module_tls = unsafe {
// FIXME(andypython): master.align
let layout = Layout::from_size_align_unchecked(master.segment_size, 16);
let ptr = alloc(layout);
ptr::copy_nonoverlapping(master.ptr, ptr, master.image_size);
ptr::write_bytes(
ptr.add(master.image_size),
0,
master.segment_size - master.image_size,
);
ptr
};
let module_tls = unsafe { alloc_zeroed(layout) };
unsafe { core::ptr::copy_nonoverlapping(master.ptr, module_tls, master.len) };
// Set the DTV entry.
tcb.dtv_mut()[dtv_index] = module_tls;
}