[libunwind] fix pc range condition check bug

[yingcong-wu]

There is an off-by-one error with current condition check for PC fallen into the range or not. There is another check within libunwind that use the correct checks in

llvm-project/libunwind/src/UnwindCursor.hpp

Line 2757 in 5050da7

if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))

      if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))

[llvmbot]

@llvm/pr-subscribers-libunwind

Author: Wu Yingcong (yingcong-wu)

Changes

There is an off-by-one error with current condition check for PC fallen into the range or not. There is another check within libunwind that use the correct checks in

llvm-project/libunwind/src/UnwindCursor.hpp

Line 2757 in 5050da7

if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))

      if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))

---

Full diff: https://github.com/llvm/llvm-project/pull/154902.diff

1 Files Affected:

• (modified) libunwind/src/DwarfParser.hpp (+1-1)

diff --git a/libunwind/src/DwarfParser.hpp b/libunwind/src/DwarfParser.hpp
index 7e85025dd054d..25250e0810987 100644
--- a/libunwind/src/DwarfParser.hpp
+++ b/libunwind/src/DwarfParser.hpp
@@ -273,7 +273,7 @@ bool CFI_Parser<A>::findFDE(A &addressSpace, pint_t pc, pint_t ehSectionStart,
           pint_t pcRange = addressSpace.getEncodedP(
               p, nextCFI, cieInfo->pointerEncoding & 0x0F);
           // Test if pc is within the function this FDE covers.
-          if ((pcStart < pc) && (pc <= pcStart + pcRange)) {
+          if ((pcStart <= pc) && (pc < pcStart + pcRange)) {
             // parse rest of info
             fdeInfo->lsda = 0;
             // check for augmentation length