[llvm] [dsymutil] Add missing validation for zero alignment section (PR #168925)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-debuginfo

Author: Ch1p (Ch111p)

<details>
<summary>Changes</summary>

Section alignments in the DWARF segment are often zero by default. Therefore, the validation logic must be placed outside the alignUp path; otherwise, dsymutil may generate an invalid Mach-O file.

---
Full diff: https://github.com/llvm/llvm-project/pull/168925.diff


1 Files Affected:

- (modified) llvm/tools/dsymutil/MachOUtils.cpp (+4-4) 


``````````diff
diff --git a/llvm/tools/dsymutil/MachOUtils.cpp b/llvm/tools/dsymutil/MachOUtils.cpp
index 362a999515683..fba698896618b 100644
--- a/llvm/tools/dsymutil/MachOUtils.cpp
+++ b/llvm/tools/dsymutil/MachOUtils.cpp
@@ -339,11 +339,11 @@ static bool createDwarfSegment(const MCAssembler& Asm,uint64_t VMAddr, uint64_t
     if (Alignment > 1) {
       VMAddr = alignTo(VMAddr, Alignment);
       FileOffset = alignTo(FileOffset, Alignment);
-      if (FileOffset > UINT32_MAX)
-        return error("section " + Sec->getName() +
-                     "'s file offset exceeds 4GB."
-                     " Refusing to produce an invalid Mach-O file.");
     }
+    if (FileOffset > UINT32_MAX)
+      return error("section " + Sec->getName() +
+                   "'s file offset exceeds 4GB."
+                   " Refusing to produce an invalid Mach-O file.");
     Writer.writeSection(Asm, *Sec, VMAddr, FileOffset, 0, 0, 0);
 
     FileOffset += Asm.getSectionAddressSize(*Sec);

``````````

</details>


https://github.com/llvm/llvm-project/pull/168925