[llvm] 3f29acb - [MachO] Improve bounds check (#141083)

[via llvm-commits]

Author: Nikita Popov
Date: 2025-05-26T09:43:00+02:00
New Revision: 3f29acb51739a3e6bfb8cc623eb37cb734c98a63

URL: https://github.com/llvm/llvm-project/commit/3f29acb51739a3e6bfb8cc623eb37cb734c98a63
DIFF: https://github.com/llvm/llvm-project/commit/3f29acb51739a3e6bfb8cc623eb37cb734c98a63.diff

LOG: [MachO] Improve bounds check (#141083)

The current check may fail if the addition overflows. I've observed
failures of macho-invalid.test on 32-bit due to this.

Instead, compare against the remaining bytes until the end of the
object.

Added: 
    

Modified: 
    llvm/lib/Object/MachOObjectFile.cpp

Removed: 
    


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diff  --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index 69d36e6a77db7..5db264207ffb7 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -192,7 +192,8 @@ static Expected<MachOObjectFile::LoadCommandInfo>
 getLoadCommandInfo(const MachOObjectFile &Obj, const char *Ptr,
                    uint32_t LoadCommandIndex) {
   if (auto CmdOrErr = getStructOrErr<MachO::load_command>(Obj, Ptr)) {
-    if (CmdOrErr->cmdsize + Ptr > Obj.getData().end())
+    assert(Ptr <= Obj.getData().end() && "Start must be before end");
+    if (CmdOrErr->cmdsize > (uintptr_t)(Obj.getData().end() - Ptr))
       return malformedError("load command " + Twine(LoadCommandIndex) +
                             " extends past end of file");
     if (CmdOrErr->cmdsize < 8)