svn commit: r276374 - head/contrib/elftoolchain/libelf

[Ed Maste]

Author: emaste
Date: Mon Dec 29 20:23:42 2014
New Revision: 276374
URL: https://svnweb.freebsd.org/changeset/base/276374

Log:
  libelf: Do not read past end of buffer
  
  Previously a corrupt ELF file could read beyond the end of e_rawfile.
  
  Upstream elftoolchain ticket 462.  Found via the security/afl fuzzer.
  
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/contrib/elftoolchain/libelf/elf_scn.c

Modified: head/contrib/elftoolchain/libelf/elf_scn.c
==============================================================================
--- head/contrib/elftoolchain/libelf/elf_scn.c	Mon Dec 29 19:38:12 2014	(r276373)
+++ head/contrib/elftoolchain/libelf/elf_scn.c	Mon Dec 29 20:23:42 2014	(r276374)
@@ -50,6 +50,7 @@ _libelf_load_section_headers(Elf *e, voi
 	Elf64_Ehdr *eh64;
 	int ec, swapbytes;
 	unsigned char *src;
+	unsigned char *rawend;
 	size_t fsz, i, shnum;
 	int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s,
 	    size_t _c, int _swap);
@@ -86,6 +87,7 @@ _libelf_load_section_headers(Elf *e, voi
 
 	swapbytes = e->e_byteorder != LIBELF_PRIVATE(byteorder);
 	src = e->e_rawfile + shoff;
+	rawend = e->e_rawfile + e->e_rawsize;
 
 	/*
 	 * If the file is using extended numbering then section #0
@@ -102,6 +104,8 @@ _libelf_load_section_headers(Elf *e, voi
 	}
 
 	for (; i < shnum; i++, src += fsz) {
+		if (src + sizeof(scn->s_shdr) > rawend)
+			return (0);
 		if ((scn = _libelf_allocate_scn(e, i)) == NULL)
 			return (0);