[llvm-branch-commits] [lld] 791fe7a - [lld-macho] Fix memcpy ub after D93267

[Fangrui Song via llvm-branch-commits]

Author: Fangrui Song
Date: 2020-12-20T20:01:20-08:00
New Revision: 791fe7ac57a9b660554219a99d63e07abfaa0982

URL: https://github.com/llvm/llvm-project/commit/791fe7ac57a9b660554219a99d63e07abfaa0982
DIFF: https://github.com/llvm/llvm-project/commit/791fe7ac57a9b660554219a99d63e07abfaa0982.diff

LOG: [lld-macho] Fix memcpy ub after D93267

Added: 
    

Modified: 
    lld/MachO/UnwindInfoSection.cpp

Removed: 
    


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diff  --git a/lld/MachO/UnwindInfoSection.cpp b/lld/MachO/UnwindInfoSection.cpp
index acb4a9d69b79..b4c3a31f8565 100644
--- a/lld/MachO/UnwindInfoSection.cpp
+++ b/lld/MachO/UnwindInfoSection.cpp
@@ -318,8 +318,9 @@ void UnwindInfoSection::writeTo(uint8_t *buf) const {
         *ep++ = (it->second << COMPRESSED_ENTRY_FUNC_OFFSET_BITS) |
                 (cuep->functionAddress - functionAddressBase);
       }
-      memcpy(ep, page.localEncodings.data(),
-             page.localEncodings.size() * sizeof(uint32_t));
+      if (page.localEncodings.size() != 0)
+        memcpy(ep, page.localEncodings.data(),
+               page.localEncodings.size() * sizeof(uint32_t));
     } else {
       auto *p2p =
           reinterpret_cast<unwind_info_regular_second_level_page_header *>(pp);