libelf: Mark shdr_flags dirty if offset or size changes during update.

We forgot to mark the shdr_flags dirty when only the sh_size or
sh_offset changed during elf_update (). This meant that if there were
no other shdr changes we only wrote out the section data, but didn't
write out the shdr table to the file.

Add a testcase that puts some sections in the reverse order and then
writes out the resulting file again without doing any other
updates. This would show the issue after write out of the
(re-reversed) ELF file (the .shstrtab section offset would be wrong
causing all section names to be garbage). Also run a self test.

Signed-off-by: Mark Wielaard <mark@klomp.org>

1 files changed, 69 insertions, 0 deletions

diff --git a/tests/run-reverse-sections.sh b/tests/run-reverse-sections.sh
new file mode 100755
index 00000000..102a1261
--- /dev/null
+++ b/tests/run-reverse-sections.sh
@@ -0,0 +1,69 @@
+#! /bin/sh
+# Copyright (C) 2019 Red Hat, Inc.
+# This file is part of elfutils.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# elfutils is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/test-subr.sh
+
+test_reverse ()
+{
+  in_file="$1"
+  out_file="${in_file}.rev"
+  out_file_mmap="${out_file}.mmap"
+
+  testfiles ${in_file}
+  tempfiles ${out_file} ${out_file_mmap}
+
+  # Reverse the offsets (the files should still be the same otherwise)
+  testrun ${abs_builddir}/elfcopy --reverse-offs ${in_file} ${out_file}
+  testrun ${abs_top_builddir}/src/elfcmp ${in_file} ${out_file}
+  testrun ${abs_top_builddir}/src/elflint --gnu ${out_file}
+  # An in-place nop will likely revert them back
+  testrun ${abs_builddir}/elfrdwrnop ${out_file}
+  testrun ${abs_top_builddir}/src/elfcmp ${in_file} ${out_file}
+  testrun ${abs_top_builddir}/src/elflint --gnu ${out_file}
+}
+
+# A collection of random testfiles to test 32/64bit, little/big endian
+# and non-ET_REL (with phdrs)/ET_REL (without phdrs).
+
+# 32bit, big endian, rel
+test_reverse testfile29
+
+# 64bit, big endian, rel
+test_reverse testfile23
+
+# 32bit, little endian, rel
+test_reverse testfile9
+
+# 64bit, little endian, rel
+test_reverse testfile38
+
+# 32bit, big endian, non-rel
+test_reverse testfile26
+
+# 64bit, big endian, non-rel
+test_reverse testfile27
+
+# 32bit, little endian, non-rel
+test_reverse testfile
+
+# 64bit, little endian, non-rel
+# Don't use testfile10. It has section headers in the middle of the file.
+# Same for testfile12. It is legal, but not the point of this testcase.
+# test_reverse testfile10
+test_reverse testfile13
+
+exit 0