[PATCH] D83742: [libunwind] Fix getSLEB128 on large values

[Ryan Prichard via Phabricator via llvm-commits]

rprichard created this revision.
Herald added projects: LLVM, libunwind.
Herald added subscribers: libcxx-commits, llvm-commits.
Herald added a reviewer: libunwind.

Previously, for large-enough values, getSLEB128 would attempt to shift
a signed int in the range [0..0x7f] by 28, 35, 42... bits, which is
undefined behavior and likely to fail.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D83742

Files:
  libunwind/src/AddressSpace.hpp


Index: libunwind/src/AddressSpace.hpp
===================================================================
--- libunwind/src/AddressSpace.hpp
+++ libunwind/src/AddressSpace.hpp
@@ -290,7 +290,7 @@
     if (p == pend)
       _LIBUNWIND_ABORT("truncated sleb128 expression");
     byte = *p++;
-    result |= ((byte & 0x7f) << bit);
+    result |= (uint64_t)(byte & 0x7f) << bit;
     bit += 7;
   } while (byte & 0x80);
   // sign extend negative numbers


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