Proposed fix

0001-Fix-fill_mmap-for-sections-past-the-section-headers.patch (text/plain), 1.69 KB, created by Lubomir Rintel on 2009-10-23 14:39:41 UTC

From 59869a0ec5f8f8bfcaea12fecd17053e3f2b1764 Mon Sep 17 00:00:00 2001
From: Lubomir Rintel <[e-mail]>
Date: Fri, 23 Oct 2009 16:18:51 +0200
Subject: [PATCH] Fix fill_mmap for sections past the section headers

If fill_mmap() was run for a section that's past the shdr_end, but does
not immediately follow the section headers the fill start would be
determined incorrectly as shdr_end, which would wipe off contents of
sections between shdr_end and current one.

Issue was reported and triaged by Hugo Mildenberger and Peter Alfredsen.
---
 libelf/ChangeLog          |    5 +++++
 libelf/elf32_updatefile.c |    7 +++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index ba38755..9463391 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,8 @@
[phone]  Lubomir Rintel  <[e-mail]>
+
+	* elf32_updatefile.c (fill_mmap): When starting past shdr_end, start
+	filling from section start, not shdr_end.
+
 2009-08-12  Mark Wielaard  <[e-mail]>
 
 	* Makefile.am (libelf.so): Use -Wl,-z,defs not -defs.
diff --git a/libelf/elf32_updatefile.c b/libelf/elf32_updatefile.c
index 0539f03..8be1994 100644
--- a/libelf/elf32_updatefile.c
+++ b/libelf/elf32_updatefile.c
@@ -322,8 +322,11 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
 
 	    if (last_position + written != scn_start + offset
 		&& shdr_end < scn_start + offset)
-	      memset (shdr_end, __libelf_fill_byte,
-		      scn_start + offset - shdr_end);
+	      {
+		char *fill_start = MAX (shdr_end, scn_start);
+		memset (fill_start, __libelf_fill_byte,
+			scn_start + offset - fill_start);
+	      }
 	  }
 
 	  if (scn->data_list_rear != NULL)
-- 
1.6.5.rc2