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

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