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using signalstack

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This commit is contained in:
Dominik Maier 2021-02-11 05:53:11 +01:00
parent fd2de83e1c
commit ce499f858f
1 changed files with 19 additions and 8 deletions
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27
afl/src/executors/inprocess.rs
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@ -195,13 +195,10 @@ pub mod unix_signals {
extern crate libc;
#[cfg(target_os = "linux")]
use fs::read_to_string;
// Unhandled signals: SIGALRM, SIGHUP, SIGINT, SIGKILL, SIGQUIT, SIGTERM
use libc::{
c_int, c_void, sigaction, siginfo_t, SA_NODEFER, SA_SIGINFO, SIGABRT, SIGBUS, SIGFPE,
SIGILL, SIGPIPE, SIGSEGV, SIGUSR2,
c_int, c_void, malloc, sigaction, sigaltstack, siginfo_t, SA_NODEFER, SA_ONSTACK,
SA_SIGINFO, SIGABRT, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV, SIGUSR2,
};
use std::{
@ -219,6 +216,10 @@ pub mod unix_signals {
state::State,
utils::Rand,
};
/// Let's get 8 mb for now.
const SIGNAL_STACK_SIZE: usize = 2 << 22;
/// To be able to handle SIGSEGV when the stack is exhausted, we need our own little stack space.
static mut SIGNAL_STACK_PTR: *const c_void = ptr::null_mut();
/// Pointers to values only needed on crash. As the program will not continue after a crash,
/// we should (tm) be okay with raw pointers here,
@ -332,7 +333,6 @@ pub mod unix_signals {
I: Input,
R: Rand,
{
println!("Setting oncrash");
CURRENT_INPUT_PTR = input as *const _ as *const c_void;
STATE_PTR = state as *mut _ as *mut c_void;
EVENT_MGR_PTR = event_mgr as *mut _ as *mut c_void;
@ -340,7 +340,6 @@ pub mod unix_signals {
#[inline]
pub unsafe fn reset_oncrash_ptrs<C, EM, FT, I, OT, R>() {
println!("Resetting oncrash");
CURRENT_INPUT_PTR = ptr::null();
STATE_PTR = ptr::null_mut();
EVENT_MGR_PTR = ptr::null_mut();
@ -356,9 +355,21 @@ pub mod unix_signals {
I: Input,
R: Rand,
{
// First, set up our own stack to be used during segfault handling. (and specify `SA_ONSTACK` in `sigaction`)
if SIGNAL_STACK_PTR.is_null() {
SIGNAL_STACK_PTR = malloc(SIGNAL_STACK_SIZE);
if SIGNAL_STACK_PTR.is_null() {
panic!(
"Failed to allocate signal stack with {} bytes!",
SIGNAL_STACK_SIZE
);
}
}
sigaltstack(SIGNAL_STACK_PTR as _, ptr::null_mut() as _);
let mut sa: sigaction = mem::zeroed();
libc::sigemptyset(&mut sa.sa_mask as *mut libc::sigset_t);
sa.sa_flags = SA_NODEFER | SA_SIGINFO;
sa.sa_flags = SA_NODEFER | SA_SIGINFO | SA_ONSTACK;
sa.sa_sigaction = libaflrs_executor_inmem_handle_crash::<C, EM, FT, I, OT, R> as usize;
for (sig, msg) in &[
(SIGSEGV, "segfault"),