[llvm-readelf/obj] - Handle out-of-order PT_LOADs better.

This is https://bugs.llvm.org/show_bug.cgi?id=45698.

Specification says that
"Loadable segment entries in the program header table appear
in ascending order, sorted on the p_vaddr member."

Our `toMappedAddr()` relies on this condition. This patch
adds a warning when the sorting order of loadable segments is wrong.
In this case we force segments sorting and that allows
`toMappedAddr()` to work as expected.

Differential revision: https://reviews.llvm.org/D92641

1 files changed, 13 insertions, 1 deletions

diff --git a/llvm/lib/Object/ELF.cpp b/llvm/lib/Object/ELF.cpp
index 116856a..28a6914 100644
--- a/llvm/lib/Object/ELF.cpp
+++ b/llvm/lib/Object/ELF.cpp
@@ -566,7 +566,8 @@ Expected<typename ELFT::DynRange> ELFFile<ELFT>::dynamicEntries() const {
 }
 
 template <class ELFT>
-Expected<const uint8_t *> ELFFile<ELFT>::toMappedAddr(uint64_t VAddr) const {
+Expected<const uint8_t *>
+ELFFile<ELFT>::toMappedAddr(uint64_t VAddr, WarningHandler WarnHandler) const {
   auto ProgramHeadersOrError = program_headers();
   if (!ProgramHeadersOrError)
     return ProgramHeadersOrError.takeError();
@@ -577,6 +578,17 @@ Expected<const uint8_t *> ELFFile<ELFT>::toMappedAddr(uint64_t VAddr) const {
     if (Phdr.p_type == ELF::PT_LOAD)
       LoadSegments.push_back(const_cast<Elf_Phdr *>(&Phdr));
 
+  auto SortPred = [](const Elf_Phdr_Impl<ELFT> *A,
+                     const Elf_Phdr_Impl<ELFT> *B) {
+    return A->p_vaddr < B->p_vaddr;
+  };
+  if (!llvm::is_sorted(LoadSegments, SortPred)) {
+    if (Error E =
+            WarnHandler("loadable segments are unsorted by virtual address"))
+      return std::move(E);
+    llvm::stable_sort(LoadSegments, SortPred);
+  }
+
   const Elf_Phdr *const *I =
       std::upper_bound(LoadSegments.begin(), LoadSegments.end(), VAddr,
                        [](uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {