From a89d508130a7c34539e8754b729f68c7658c9a19 Mon Sep 17 00:00:00 2001
From: Pablo Galindo <pablogsal@gmail.com>
Date: Tue, 22 Sep 2020 01:22:42 +0100
Subject: [PATCH] Handle libraries with more than one .shstrtab section

---
 src/patchelf.cc          | 12 +++++++++---
 tests/Makefile.am        | 10 +++++++---
 tests/too-many-strtab.c  |  3 +++
 tests/too-many-strtab.sh | 21 +++++++++++++++++++++
 4 files changed, 40 insertions(+), 6 deletions(-)
 create mode 100644 tests/too-many-strtab.c
 create mode 100755 tests/too-many-strtab.sh

diff --git a/src/patchelf.cc b/src/patchelf.cc
index 0af9f0a5..80ada220 100644
--- a/src/patchelf.cc
+++ b/src/patchelf.cc
@@ -495,7 +495,7 @@ void ElfFile<ElfFileParamNames>::sortShdrs()
             info[getSectionName(shdrs[i])] = getSectionName(shdrs[rdi(shdrs[i].sh_info)]);
 
     /* Idem for the index of the .shstrtab section in the ELF header. */
-    SectionName shstrtabName = getSectionName(shdrs[rdi(hdr->e_shstrndx)]);
+    Elf_Shdr shstrtab = shdrs[rdi(hdr->e_shstrndx)];
 
     /* Sort the sections by offset. */
     CompShdr comp;
@@ -515,8 +515,14 @@ void ElfFile<ElfFileParamNames>::sortShdrs()
             wri(shdrs[i].sh_info,
                 findSection3(info[getSectionName(shdrs[i])]));
 
-    /* And the .shstrtab index. */
-    wri(hdr->e_shstrndx, findSection3(shstrtabName));
+    /* And the .shstrtab index. Note: the match here is done by checking the offset as searching
+     * by name can yield incorrect results in case there are multiple sections with the same
+     * name as the one initially pointed by hdr->e_shstrndx */
+    for (unsigned int i = 1; i < rdi(hdr->e_shnum); ++i) {
+        if (shdrs[i].sh_offset == shstrtab.sh_offset) {
+            wri(hdr->e_shstrndx, i);
+        }
+    }
 }
 
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index dbb7580e..47947a1b 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,6 +1,6 @@
 LIBS =
 
-check_PROGRAMS = simple main main-scoped big-dynstr no-rpath
+check_PROGRAMS = simple main too-many-strtab main-scoped big-dynstr no-rpath
 
 no_rpath_arch_TESTS = \
   no-rpath-amd64.sh \
@@ -25,7 +25,8 @@ src_TESTS = \
   force-rpath.sh \
   plain-needed.sh \
   output-flag.sh \
-  build-id.sh
+  build-id.sh \
+  too-many-strtab.sh
 
 build_TESTS = \
   $(no_rpath_arch_TESTS)
@@ -77,7 +78,7 @@ big_dynstr_LDFLAGS = $(LDFLAGS_local)
 # - without libtool, only archives (static libraries) can be built by automake
 # - with libtool, it is difficult to control options
 # - with libtool, it is not possible to compile convenience *dynamic* libraries :-(
-check_PROGRAMS += libfoo.so libfoo-scoped.so libbar.so libbar-scoped.so libsimple.so libbuildid.so
+check_PROGRAMS += libfoo.so libfoo-scoped.so libbar.so libbar-scoped.so libsimple.so libbuildid.so libtoomanystrtab.so
 
 libbuildid_so_SOURCES = simple.c
 libbuildid_so_LDFLAGS = $(LDFLAGS_sharedlib) -Wl,-build-id
@@ -101,6 +102,9 @@ libbar_scoped_so_LDFLAGS = $(LDFLAGS_sharedlib)
 libsimple_so_SOURCES = simple.c
 libsimple_so_LDFLAGS = $(LDFLAGS_sharedlib)
 
+libtoomanystrtab_so_SOURCES = too-many-strtab.c
+libtoomanystrtab_so_LDFLAGS = $(LDFLAGS_sharedlib)
+
 no_rpath_SOURCES = no-rpath.c
 # no -fpic for no-rpath.o
 no_rpath_CFLAGS =
diff --git a/tests/too-many-strtab.c b/tests/too-many-strtab.c
new file mode 100644
index 00000000..0f513168
--- /dev/null
+++ b/tests/too-many-strtab.c
@@ -0,0 +1,3 @@
+const int __attribute__((section (".shstrtab"))) lel = 42;
+
+int main(){return 0;}
diff --git a/tests/too-many-strtab.sh b/tests/too-many-strtab.sh
new file mode 100755
index 00000000..3ef158f7
--- /dev/null
+++ b/tests/too-many-strtab.sh
@@ -0,0 +1,21 @@
+#! /bin/sh -e
+SCRATCH=scratch/$(basename $0 .sh)
+
+rm -rf ${SCRATCH}
+mkdir -p ${SCRATCH}
+
+cp libtoomanystrtab.so ${SCRATCH}/
+
+# Set a RUNPATH on the library
+../src/patchelf --set-rpath '$ORIGIN' ${SCRATCH}/libtoomanystrtab.so
+
+# Check that patchelf is able to patch it again without crashing. Previously,
+# it will wrongly identify the lib as a static object because there was no
+# .dynamic section
+exitCode=0
+(../src/patchelf --set-rpath '$ORIGIN' ${SCRATCH}/libtoomanystrtab.so) || exitCode=$?
+if test "$exitCode" != 0; then
+    echo "bad exit code!"
+    exit 1
+fi
+