[llvm] 2667be0 - [JITLink][MachO] Error on N_EXT symbols with illegal string-table index 0.

[Lang Hames via llvm-commits]

Author: Lang Hames
Date: 2023-01-28T19:58:27-08:00
New Revision: 2667be0eb85b65f95d5cf303162219d067de11ae

URL: https://github.com/llvm/llvm-project/commit/2667be0eb85b65f95d5cf303162219d067de11ae
DIFF: https://github.com/llvm/llvm-project/commit/2667be0eb85b65f95d5cf303162219d067de11ae.diff

LOG: [JITLink][MachO] Error on N_EXT symbols with illegal string-table index 0.

Index 0 is reserved for anonymous symbols, which can't have the N_EXT bit
set (since N_EXT means non-local scope, and non-local scope requires a name).

Added: 
    llvm/test/ExecutionEngine/JITLink/X86/MachO_unnamed_external.yaml

Modified: 
    llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
index 9876899933979..a520008aeb001 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
@@ -267,7 +267,11 @@ Error MachOLinkGraphBuilder::createNormalizedSymbols() {
         Name = *NameOrErr;
       else
         return NameOrErr.takeError();
-    }
+    } else if (Type & MachO::N_EXT)
+      return make_error<JITLinkError>("Symbol at index " +
+                                      formatv("{0}", SymbolIndex) +
+                                      " has no name (string table index 0), "
+                                      "but N_EXT bit is set");
 
     LLVM_DEBUG({
       dbgs() << "  ";

diff  --git a/llvm/test/ExecutionEngine/JITLink/X86/MachO_unnamed_external.yaml b/llvm/test/ExecutionEngine/JITLink/X86/MachO_unnamed_external.yaml
new file mode 100644
index 0000000000000..771a22ba8f3f1
--- /dev/null
+++ b/llvm/test/ExecutionEngine/JITLink/X86/MachO_unnamed_external.yaml
@@ -0,0 +1,109 @@
+# RUN: yaml2obj %s -o %t
+# RUN: not llvm-jitlink -noexec -entry _anchor %t 2>&1 | FileCheck %s
+
+# Test that we generate an error (rather than crashing) if we encounter a
+# symbol with a string index of zero (no name) with the N_EXT bit set.
+
+# CHECK: Symbol at index 1 has no name (string table index 0), but N_EXT bit
+
+--- !mach-o
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+LoadCommands:
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+    filesize:        0
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+        content:         ''
+      - sectname:        __common
+        segname:         __DATA
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+LinkEditData:
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+  StringTable:
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+    - _anchor
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+...