fix binaries without .gnu.hash section

Author: Mic92

src/patchelf.cc

@@ -1106,9 +1106,12 @@ void ElfFile<ElfFileParamNames>::rewriteHeaders(Elf_Addr phdrAddress)
                 dyn->d_un.d_ptr = findSection(".dynsym").sh_addr;
             else if (d_tag == DT_HASH)
                 dyn->d_un.d_ptr = findSection(".hash").sh_addr;
-            else if (d_tag == DT_GNU_HASH)
-                dyn->d_un.d_ptr = findSection(".gnu.hash").sh_addr;
-            else if (d_tag == DT_JMPREL) {
+            else if (d_tag == DT_GNU_HASH) {
+                auto shdr = findSection2(".gnu.hash");
+                // some binaries might this section stripped
+                // in which case we just ignore the value.
+                if (shdr) dyn->d_un.d_ptr = shdr->sh_addr;
+            } else if (d_tag == DT_JMPREL) {
                 auto shdr = findSection2(".rel.plt");
                 if (!shdr) shdr = findSection2(".rela.plt"); /* 64-bit Linux, x86-64 */
                 if (!shdr) shdr = findSection2(".rela.IA_64.pltoff"); /* 64-bit Linux, IA-64 */

tests/Makefile.am

@@ -30,7 +30,8 @@ src_TESTS = \
   build-id.sh \
   invalid-elf.sh \
   endianness.sh \
-  contiguous_note_sections.sh
+  contiguous_note_sections.sh \
+  no-gnu-hash.sh
 
 build_TESTS = \
   $(no_rpath_arch_TESTS)

tests/no-gnu-hash.sh

@@ -0,0 +1,13 @@
+#! /bin/sh -e
+SCRATCH=scratch/$(basename $0 .sh)
+
+rm -rf ${SCRATCH}
+mkdir -p ${SCRATCH}
+
+cp simple ${SCRATCH}/
+
+strip --remove-section=.gnu.hash ${SCRATCH}/simple
+
+# Check if patchelf handles binaries with GNU_HASH in dynamic section but
+# without .gnu.hash section
+../src/patchelf --set-interpreter /oops ${SCRATCH}/simple