[compiler-rt] 4ecfa0a - [sanitizers] Fix integer underflow when parsing ELF.

[Florian Mayer via llvm-commits]

Author: Florian Mayer
Date: 2022-01-04T21:47:02-08:00
New Revision: 4ecfa0a0c5fba0acad8c902d49243c60b6ccd34e

URL: https://github.com/llvm/llvm-project/commit/4ecfa0a0c5fba0acad8c902d49243c60b6ccd34e
DIFF: https://github.com/llvm/llvm-project/commit/4ecfa0a0c5fba0acad8c902d49243c60b6ccd34e.diff

LOG: [sanitizers] Fix integer underflow when parsing ELF.

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D116639

Added: 
    

Modified: 
    compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp

Removed: 
    


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diff  --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
index 3c15c35cf4887..06654ea5ea100 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
@@ -605,7 +605,7 @@ static int AddModuleSegments(const char *module_name, dl_phdr_info *info,
                                  writable);
     } else if (phdr->p_type == PT_NOTE) {
       uptr off = 0;
-      while (off < phdr->p_memsz - sizeof(ElfW(Nhdr))) {
+      while (off + sizeof(ElfW(Nhdr)) < phdr->p_memsz) {
         auto *nhdr = reinterpret_cast<const ElfW(Nhdr) *>(info->dlpi_addr +
                                                           phdr->p_vaddr + off);
         constexpr auto kGnuNamesz = 4;  // "GNU" with NUL-byte.