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never_zero

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This commit is contained in:
Dominik Maier 2021-01-05 01:28:05 +01:00
parent abe027ad95
commit fde6201d74
1 changed files with 7 additions and 2 deletions
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9
afl/src/executors/runtime.rs
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@ -15,7 +15,7 @@ pub static mut __lafl_max_edges_size: u32 = 0;
#[inline]
pub unsafe extern "C" fn __sanitizer_cov_trace_pc_guard(guard: &u32) {
let ref mut trace_byte = *__lafl_edges_map.offset(*guard as isize);
/* TODO: translate to RUST inline ASM
/* TODO: translate to RUST inline ASM once it's stable (neverzero)
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
asm! volatile( \
"addb $1, (%0, %1, 1)\n" \
@ -26,7 +26,12 @@ pub unsafe extern "C" fn __sanitizer_cov_trace_pc_guard(guard: &u32) {
#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
*/
*trace_byte = (*trace_byte).wrapping_add(1);
// Make sure we wrap to 0, not zero, it's empirically proven to be better for fuzzing.
let added = (*trace_byte as u16) + 1;
*trace_byte = (added as u8) + (added >> 8) as u8;
//*trace_byte = (*trace_byte).wrapping_add(1);
}
#[no_mangle]