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Check for multiplication integer overflow in CHECK_EHDR

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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
This commit is contained in:
Ed Maste 2014-12-30 22:04:24 +00:00
parent ee8c7bb573
commit 6db8a9f3a5
1 changed files with 2 additions and 4 deletions
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6
contrib/elftoolchain/libelf/elf_scn.c
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@ -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, void *ehdr)
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, void *ehdr)
#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, void *ehdr)
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, void *ehdr)
}
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);