Author: emaste
Date: Tue Dec 30 22:04:24 2014
New Revision: 276427
URL: https://svnweb.freebsd.org/changeset/base/276427
Log:
Check for multiplication integer overflow in CHECK_EHDR
The initial fix in r276374 is valid only for 64-bit objects. Revert it
and return an error in CHECK_EHDR if the multiplication would overflow.
The original buffer overflow issue was found with the security/afl
fuzzer and has upstream elftoolchain ticket 462. The 32-bit object issue
with r276374 found by antoine@ during an i386 exp-run.
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 Tue Dec 30 21:55:50 2014
(r276426)
+++ head/contrib/elftoolchain/libelf/elf_scn.c Tue Dec 30 22:04:24 2014
(r276427)
@@ -32,6 +32,7 @@
#include <gelf.h>
#include <libelf.h>
#include <stddef.h>
+#include <stdint.h>
#include <stdlib.h>
#include "_libelf.h"
@@ -50,7 +51,6 @@ _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);
@@ -61,6 +61,7 @@ _libelf_load_section_headers(Elf *e, voi
#define CHECK_EHDR(E,EH) do { \
if (fsz != (EH)->e_shentsize || \
+ shnum > SIZE_MAX / fsz || \
shoff + fsz * shnum > e->e_rawsize) { \
LIBELF_SET_ERROR(HEADER, 0); \
return (0); \
@@ -87,7 +88,6 @@ _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
@@ -104,8 +104,6 @@ _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);
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