T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

debug: Avoid underflow when scanning for landing pad bytes (#2866)

Browse Source
This commit is contained in:
Benjamin Bouvier
2021-05-03 18:58:40 +02:00
committed by GitHub
parent dfb1bc4d02
commit 8811246a9f
1 changed files with 16 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
crates/debug/src/transform/expression.rs
View File

@@ -512,24 +512,28 @@ where
}
};
}
// Find all landing pads by scanning bytes, do not care about
// false location at this moment.
// Looks hacky but it is fast; does not need to be really exact.
for i in 0..buf.len() - 2 {
let op = buf[i];
if op == gimli::constants::DW_OP_bra.0 || op == gimli::constants::DW_OP_skip.0 {
// TODO fix for big-endian
let offset = i16::from_le_bytes([buf[i + 1], buf[i + 2]]);
let origin = i + 3;
// Discarding out-of-bounds jumps (also some of falsely detected ops)
if (offset >= 0 && offset as usize + origin <= buf.len())
|| (offset < 0 && -offset as usize <= origin)
{
let target = buf.len() as isize - origin as isize - offset as isize;
jump_targets.insert(target as u64, JumpTargetMarker::new());
if buf.len() > 2 {
for i in 0..buf.len() - 2 {
let op = buf[i];
if op == gimli::constants::DW_OP_bra.0 || op == gimli::constants::DW_OP_skip.0 {
// TODO fix for big-endian
let offset = i16::from_le_bytes([buf[i + 1], buf[i + 2]]);
let origin = i + 3;
// Discarding out-of-bounds jumps (also some of falsely detected ops)
if (offset >= 0 && offset as usize + origin <= buf.len())
|| (offset < 0 && -offset as usize <= origin)
{
let target = buf.len() as isize - origin as isize - offset as isize;
jump_targets.insert(target as u64, JumpTargetMarker::new());
}
}
}
}
while !pc.is_empty() {
let unread_bytes = pc.len().into_u64();
if let Some(marker) = jump_targets.get(&unread_bytes) {