https://bugs.gentoo.org/666954
https://github.com/rpm-software-management/rpm/issues/423
https://sourceware.org/ml/elfutils-devel/2019-q2/msg00077.html

From: Mark Wielaard <mark at klomp dot org>
Subject: [PATCH] libelf: Mark shdr_flags dirty if offset or size changes during update.
Date: Mon, 13 May 2019 00:13:42 +0200
Message-Id: <20190512221342.23383-1-mark@klomp.org>

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.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 libelf/elf32_updatenull.c          |   5 +-

--- a/libelf/elf32_updatenull.c
+++ b/libelf/elf32_updatenull.c
@@ -366,12 +366,15 @@ __elfw2(LIBELFBITS,updatenull_wrlock) (Elf *elf, int *change_bop, size_t shnum)
 		    }
 
 		  /* See whether the section size is correct.  */
+		  int size_changed = 0;
 		  update_if_changed (shdr->sh_size, (GElf_Word) offset,
-				     changed);
+				     size_changed);
+		  changed |= size_changed;
 
 		  if (shdr->sh_type != SHT_NOBITS)
 		    size += offset;
 
+		  scn->shdr_flags |= (offset_changed | size_changed);
 		  scn->flags |= changed;
 		}