From: Mark Wielaard <mark@klomp.org>
Date: Tue, 7 Apr 2026 13:25:53 +0000 (+0200)
Subject: libebl: Explicitly check Ehdr can be used in eblopenbackend
X-Git-Tag: elfutils-0.195~14
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=f0f77b818f99de2e75d98758f96cb2b6da87fe65;p=thirdparty%2Felfutils.git

libebl: Explicitly check Ehdr can be used in eblopenbackend

Make sure Ehdr is really read into memory, don't use internal elf
state.

	* libebl/eblopenbackend.c (openbackend): Use gelf_getehdr
	instead of accessing elf state ehdr field directly.

https://sourceware.org/bugzilla/show_bug.cgi?id=34007

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

diff --git a/libebl/eblopenbackend.c b/libebl/eblopenbackend.c
index dbe4b947..e2a50321 100644
--- a/libebl/eblopenbackend.c
+++ b/libebl/eblopenbackend.c
@@ -309,17 +309,9 @@ openbackend (Elf *elf, const char *emulation, GElf_Half machine)
 	/* Well, we know the emulation name now.  */
 	result->emulation = machines[cnt].emulation;
 
-	/* We access some data structures directly.  Make sure the 32 and
-	   64 bit variants are laid out the same.  */
-	eu_static_assert (offsetof (Elf32_Ehdr, e_machine)
-			  == offsetof (Elf64_Ehdr, e_machine));
-	eu_static_assert (sizeof (((Elf32_Ehdr *) 0)->e_machine)
-			  == sizeof (((Elf64_Ehdr *) 0)->e_machine));
-	eu_static_assert (offsetof (Elf, state.elf32.ehdr)
-			  == offsetof (Elf, state.elf64.ehdr));
-
 	/* Prefer taking the information from the ELF file.  */
-	if (elf == NULL)
+	GElf_Ehdr ehdr;
+	if (elf == NULL || gelf_getehdr (elf, &ehdr) == NULL)
 	  {
 	    result->machine = machines[cnt].em;
 	    result->class = machines[cnt].class;
@@ -327,9 +319,9 @@ openbackend (Elf *elf, const char *emulation, GElf_Half machine)
 	  }
 	else
 	  {
-	    result->machine = elf->state.elf32.ehdr->e_machine;
-	    result->class = elf->state.elf32.ehdr->e_ident[EI_CLASS];
-	    result->data = elf->state.elf32.ehdr->e_ident[EI_DATA];
+	    result->machine = ehdr.e_machine;
+	    result->class = ehdr.e_ident[EI_CLASS];
+	    result->data = ehdr.e_ident[EI_DATA];
 	  }
 
         if (machines[cnt].init &&