Skip empty PT_NOTE sections

src/patchelf.cc

@@ -894,6 +894,14 @@ void ElfFile<ElfFileParamNames>::normalizeNoteSegments()
         size_t start_off = rdi(phdr.p_offset);
         size_t curr_off = start_off;
         size_t end_off = start_off + rdi(phdr.p_filesz);
+
+        /* Binaries produced by older patchelf versions may contain empty PT_NOTE segments.
+           For backwards compatibility, if we find one we should ignore it. */
+        bool empty = std::none_of(shdrs.begin(), shdrs.end(),
+            [&](auto & shdr) { return rdi(shdr.sh_offset) >= start_off && rdi(shdr.sh_offset) < end_off; });
+        if (empty)
+            continue;
+
         while (curr_off < end_off) {
             /* Find a section that starts at the current offset. If we can't
                find one, it means the SHT_NOTE sections weren't contiguous

tests/Makefile.am

@@ -42,14 +42,15 @@ src_TESTS = \
   phdr-corruption.sh \
   replace-needed.sh \
   replace-add-needed.sh \
-  add-debug-tag.sh
+  add-debug-tag.sh \
+  empty-note.sh
 
 build_TESTS = \
   $(no_rpath_arch_TESTS)
 
 TESTS = $(src_TESTS) $(build_TESTS)
 
-EXTRA_DIST = no-rpath-prebuild $(src_TESTS) no-rpath-prebuild.sh invalid-elf endianness
+EXTRA_DIST = no-rpath-prebuild $(src_TESTS) no-rpath-prebuild.sh invalid-elf endianness empty-note
 
 TESTS_ENVIRONMENT = PATCHELF_DEBUG=1
 

tests/empty-note.sh

@@ -0,0 +1,12 @@
+#! /bin/sh -e
+
+SCRATCH=scratch/$(basename $0 .sh)
+
+rm -rf ${SCRATCH}
+mkdir -p ${SCRATCH}
+cp $(dirname $(readlink -f $0))/empty-note ${SCRATCH}/
+
+# Running --set-interpreter on this binary should not produce the following
+# error:
+# patchelf: cannot normalize PT_NOTE segment: non-contiguous SHT_NOTE sections
+../src/patchelf --set-interpreter ld-linux-x86-64.so.2 ${SCRATCH}/empty-note