Bug 24042 - Global-buffer-overflow problem in function output_rel_find in eelf_x86_64.c, as demonstrated by "ld -E"
Summary: Global-buffer-overflow problem in function output_rel_find in eelf_x86_64.c, ...
Status: RESOLVED FIXED
Alias: None
Product: binutils
Classification: Unclassified
Component: ld (show other bugs)
Version: 2.31
: P2 normal
Target Milestone: 2.32
Assignee: Alan Modra
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-12-28 09:13 UTC by wcventure
Modified: 2018-12-31 07:29 UTC (History)
0 users

See Also:
Host:
Target:
Build:
Last reconfirmed: 2018-12-31 00:00:00


Attachments
POC1 (177 bytes, application/octet-stream)
2018-12-28 09:13 UTC, wcventure
Details
POC2 (173 bytes, application/octet-stream)
2018-12-28 09:14 UTC, wcventure
Details

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Description wcventure 2018-12-28 09:13:55 UTC
Created attachment 11497 [details]
POC1

Hi, there.

A Global-buffer-overflow problem was discovered in function output_rel_find in eelf_x86_64.c of binutils 2.31. This problem can be reproduced in the latest code base, too. A crafted ELF input can cause segment faults and I have confirmed them with address sanitizer too.

Please use the "./ld -E $POC" to reproduce the bug.


The ASAN dumps the stack trace as follows:

> =================================================================
> ==24959==ERROR: AddressSanitizer: global-buffer-overflow on address 0x000000b0f044 at pc 0x0000004a3889 bp 0x7ffd29777410 sp 0x7ffd29777400
> READ of size 1 at 0x000000b0f044 thread T0
>     #0 0x4a3888 in output_rel_find /binutils-2.31_ASAN/ld/eelf_x86_64.c:1802
>     #1 0x4a5cb8 in gldelf_x86_64_place_orphan /binutils-2.31_ASAN/ld/eelf_x86_64.c:2138
>     #2 0x47fd79 in ldemul_place_orphan /binutils-2.31_ASAN/ld/ldemul.c:130
>     #3 0x45580d in ldlang_place_orphan /binutils-2.31_ASAN/ld/ldlang.c:6497
>     #4 0x455f08 in lang_place_orphans /binutils-2.31_ASAN/ld/ldlang.c:6554
>     #5 0x45a679 in lang_process /binutils-2.31_ASAN/ld/ldlang.c:7349
>     #6 0x469dbd in main ldmain.c:438
>     #7 0x7fa2ca96182f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
>     #8 0x4036d8 in _start (/binutils-2.31_ASAN/build/bin/ld+0x4036d8)
> 
> 0x000000b0f044 is located 3 bytes to the right of global variable '*.LC0' defined in 'elf.c' (0xb0f040) of size 1
>   '*.LC0' is ascii string ''
> 0x000000b0f044 is located 60 bytes to the left of global variable '*.LC10' defined in 'elf.c' (0xb0f080) of size 67
>   '*.LC10' is ascii string '%pB: attempt to load strings from a non-string section (number %d)'
> SUMMARY: AddressSanitizer: global-buffer-overflow /binutils-2.31_ASAN/ld/eelf_x86_64.c:1802 output_rel_find
> Shadow bytes around the buggy address:
>   0x000080159db0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x000080159dc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x000080159dd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x000080159de0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x000080159df0: 06 f9 f9 f9 f9 f9 f9 f9 00 00 01 f9 f9 f9 f9 f9
> =>0x000080159e00: 06 f9 f9 f9 f9 f9 f9 f9[01]f9 f9 f9 f9 f9 f9 f9
>   0x000080159e10: 00 00 00 00 00 00 00 00 03 f9 f9 f9 f9 f9 f9 f9
>   0x000080159e20: 04 f9 f9 f9 f9 f9 f9 f9 00 02 f9 f9 f9 f9 f9 f9
>   0x000080159e30: 00 00 00 00 00 00 06 f9 f9 f9 f9 f9 00 00 00 00
>   0x000080159e40: 00 00 00 00 06 f9 f9 f9 f9 f9 f9 f9 07 f9 f9 f9
>   0x000080159e50: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
> Shadow byte legend (one shadow byte represents 8 application bytes):
>   Addressable:           00
>   Partially addressable: 01 02 03 04 05 06 07
>   Heap left redzone:       fa
>   Heap right redzone:      fb
>   Freed heap region:       fd
>   Stack left redzone:      f1
>   Stack mid redzone:       f2
>   Stack right redzone:     f3
>   Stack partial redzone:   f4
>   Stack after return:      f5
>   Stack use after scope:   f8
>   Global redzone:          f9
>   Global init order:       f6
>   Poisoned by user:        f7
>   Container overflow:      fc
>   Array cookie:            ac
>   Intra object redzone:    bb
>   ASan internal:           fe
> ==24959==ABORTING
Comment 1 wcventure 2018-12-28 09:14:21 UTC
Created attachment 11498 [details]
POC2
Comment 2 cvs-commit@gcc.gnu.org 2018-12-31 07:28:03 UTC
The master branch has been updated by Alan Modra <amodra@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=8fd04a4255376036e85c4e80d430b44ec4b06c64

commit 8fd04a4255376036e85c4e80d430b44ec4b06c64
Author: Alan Modra <amodra@gmail.com>
Date:   Mon Dec 31 17:06:25 2018 +1030

    PR24042, Global-buffer-overflow problem in output_rel_find
    
    place_orphan handled ELF SHT_REL/SHT_RELA specially, output_rel_find
    didn't.  This mismatch was a bug and also meant it was possible to
    craft an object where ld accessed section->name out of bounds.
    
    	PR 24042
    	* emultempl/elf32.em (output_rel_find): Drop "sec" param.  Add
    	"rela".
    	(gld${EMULATION_NAME}_place_orphan): Use sh_type to calculate
    	"rela" param of output_rel_find when ELF.  Tidy uses of elfinput.
Comment 3 Alan Modra 2018-12-31 07:29:09 UTC
Fixed