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Fix sigreturn for x86 #668

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Fix sigreturn for x86 #668

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5925ef0
fix sigreturn for x86
CvvT Feb 18, 2026
b4920d4
use wrapping_sub
CvvT Feb 18, 2026
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9 changes: 5 additions & 4 deletions litebox_shim_linux/src/syscalls/signal/x86.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,8 @@ struct SignalFrameRt {
impl Task {
/// Legacy signal return syscall implementation for x86.
pub(crate) fn sys_sigreturn(&self, ctx: &mut PtRegs) -> Result<usize, Errno> {
let lctx_addr = ctx.esp.wrapping_sub(8);
let sigframe_addr = ctx.esp.wrapping_sub(8);
let lctx_addr = sigframe_addr.wrapping_add(offset_of!(SignalFrame, context));
let lctx_ptr = ConstPtr::<LegacyContext>::from_usize(lctx_addr);
let Some(lctx) = lctx_ptr.read_at_offset(0) else {
self.force_signal(Signal::SIGSEGV, false);
Expand Down Expand Up @@ -73,14 +74,14 @@ pub(super) fn get_signal_frame(sp: usize, action: &SigAction) -> usize {

// Space for the signal frame.
if action.flags.contains(SaFlags::SIGINFO) {
frame_addr -= core::mem::size_of::<SignalFrameRt>();
frame_addr = frame_addr.wrapping_sub(core::mem::size_of::<SignalFrameRt>());
} else {
frame_addr -= core::mem::size_of::<SignalFrame>();
frame_addr = frame_addr.wrapping_sub(core::mem::size_of::<SignalFrame>());
}

// Align the frame (offset by 4 bytes for return address).
frame_addr &= !15;
frame_addr -= 4;
frame_addr = frame_addr.wrapping_sub(4);

frame_addr
}
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6 changes: 3 additions & 3 deletions litebox_shim_linux/src/syscalls/signal/x86_64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,14 +32,14 @@ pub(super) fn get_signal_frame(sp: usize, _action: &SigAction) -> usize {
let mut frame_addr = sp;

// Skip the redzone.
frame_addr -= 128;
frame_addr = frame_addr.wrapping_sub(128);

// Space for the signal frame.
frame_addr -= core::mem::size_of::<SignalFrame>();
frame_addr = frame_addr.wrapping_sub(core::mem::size_of::<SignalFrame>());

// Align the frame (offset by 8 bytes for return address)
frame_addr &= !15;
frame_addr -= 8;
frame_addr = frame_addr.wrapping_sub(8);

frame_addr
}
Expand Down