[systemd-devel] [PATCH] test-dhcp6-client: Fix option length

Fri Aug 29 05:58:54 PDT 2014

On Fri, Aug 29, 2014 at 09:20:46AM +0300, Patrik Flykt wrote:
> The whole DHCPv6 test message length was incorrectly used as the length
> of DHCPv6 options causing the following bad memory access:
> 
> $ build/test-dhcp6-client
> Assertion 'interface_index >= -1' failed at ../src/libsystemd-network/sd-dhcp6-client.c:129, function sd_dhcp6_client_set_index(). Ignoring.
> =================================================================
> ==29135==ERROR: AddressSanitizer: global-buffer-overflow on address 0x7fe204aa9148 at pc 0x7fe204a5958f bp 0x7fff3e47d470 sp 0x7fff3e47d460
> READ of size 1 at 0x7fe204aa9148 thread T0
>     #0 0x7fe204a5958e in option_parse_hdr ../src/libsystemd-network/dhcp6-option.c:145
>     #1 0x7fe204a59884 in dhcp6_option_parse ../src/libsystemd-network/dhcp6-option.c:165
>     #2 0x7fe204a4eb9c in test_advertise_option ../src/libsystemd-network/test-dhcp6-client.c:227
>     #3 0x7fe204a51c58 in main ../src/libsystemd-network/test-dhcp6-client.c:584
>     #4 0x7fe2031590df in __libc_start_main (/lib64/libc.so.6+0x200df)
>     #5 0x7fe204a4cc5b (/home/test/systemd/build/test-dhcp6-client+0x25c5b)
> 
> 0x7fe204aa9148 is located 2 bytes to the right of global variable 'msg_advertise' from '../src/libsystemd-network/test-dhcp6-client.c' (0x7fe204aa9080) of size 198
> 0x7fe204aa9148 is located 56 bytes to the left of global variable 'msg_reply' from '../src/libsystemd-network/test-dhcp6-client.c' (0x7fe204aa9180) of size 173
> SUMMARY: AddressSanitizer: global-buffer-overflow ../src/libsystemd-network/dhcp6-option.c:145 option_parse_hdr
> ---
> 
> This seems to be the cause of the bad memory access, please test.
Hm, I thiink it helps, but there's another one:

$ build/test-dhcp6-client 
Assertion 'interface_index >= -1' failed at ../src/libsystemd-network/sd-dhcp6-client.c:129, function sd_dhcp6_client_set_index(). Ignoring.
DHCPv6 CLIENT: Sent SOLICIT
DHCPv6 CLIENT: Next retransmission in 1.049185s
=================================================================
==29571==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x611000009708 at pc 0x7fd00190458f bp 0x7fff287de8d0 sp 0x7fff287de8c0
READ of size 1 at 0x611000009708 thread T0
    #0 0x7fd00190458e in option_parse_hdr ../src/libsystemd-network/dhcp6-option.c:145
    #1 0x7fd001904884 in dhcp6_option_parse ../src/libsystemd-network/dhcp6-option.c:165
    #2 0x7fd0019008ff in client_parse_message ../src/libsystemd-network/sd-dhcp6-client.c:582
    #3 0x7fd001901078 in client_receive_advertise ../src/libsystemd-network/sd-dhcp6-client.c:732
    #4 0x7fd001901822 in client_receive_message ../src/libsystemd-network/sd-dhcp6-client.c:809
    #5 0x7fd001918c77 in source_dispatch ../src/libsystemd/sd-event/sd-event.c:2035
    #6 0x7fd00191b7f1 in sd_event_dispatch ../src/libsystemd/sd-event/sd-event.c:2384
    #7 0x7fd00191bad4 in sd_event_run ../src/libsystemd/sd-event/sd-event.c:2413
    #8 0x7fd00191bc1d in sd_event_loop ../src/libsystemd/sd-event/sd-event.c:2428
    #9 0x7fd0018fca81 in test_client_solicit ../src/libsystemd-network/test-dhcp6-client.c:562
    #10 0x7fd0018fcc65 in main ../src/libsystemd-network/test-dhcp6-client.c:585
    #11 0x7fd0000040df in __libc_start_main (/lib64/libc.so.6+0x200df)
    #12 0x7fd0018f7c5b (/home/test/systemd/build/test-dhcp6-client+0x25c5b)

0x611000009708 is located 2 bytes to the right of 198-byte region [0x611000009640,0x611000009706)
allocated by thread T0 here:
    #0 0x7fd000827cf5 in calloc (/lib64/libasan.so.1+0x57cf5)
    #1 0x7fd00190152b in client_receive_message ../src/libsystemd-network/sd-dhcp6-client.c:769
    #2 0x7fd001918c77 in source_dispatch ../src/libsystemd/sd-event/sd-event.c:2035
    #3 0x7fd00191b7f1 in sd_event_dispatch ../src/libsystemd/sd-event/sd-event.c:2384
    #4 0x7fd00191bad4 in sd_event_run ../src/libsystemd/sd-event/sd-event.c:2413
    #5 0x7fd00191bc1d in sd_event_loop ../src/libsystemd/sd-event/sd-event.c:2428
    #6 0x7fd0018fca81 in test_client_solicit ../src/libsystemd-network/test-dhcp6-client.c:562
    #7 0x7fd0018fcc65 in main ../src/libsystemd-network/test-dhcp6-client.c:585
    #8 0x7fd0000040df in __libc_start_main (/lib64/libc.so.6+0x200df)

SUMMARY: AddressSanitizer: heap-buffer-overflow ../src/libsystemd-network/dhcp6-option.c:145 option_parse_hdr
Shadow bytes around the buggy address:
  0x0c227fff9290: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff92a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff92b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff92c0: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
  0x0c227fff92d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c227fff92e0: 06[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff92f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c227fff9300: 00 00 00 00 00 00 00 00 00 00 00 00 fa fa fa fa
  0x0c227fff9310: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
  0x0c227fff9320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c227fff9330: 00 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa
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
  Contiguous container OOB:fc
  ASan internal:           fe
==29571==ABORTING

Zbyszek

>  src/libsystemd-network/test-dhcp6-client.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/libsystemd-network/test-dhcp6-client.c b/src/libsystemd-network/test-dhcp6-client.c
> index 96c68e1..259db33 100644
> --- a/src/libsystemd-network/test-dhcp6-client.c
> +++ b/src/libsystemd-network/test-dhcp6-client.c
> @@ -207,7 +207,7 @@ static int test_advertise_option(sd_event *e) {
>          DHCP6Message *advertise = (DHCP6Message *)msg_advertise;
>          uint8_t *optval, *opt = &msg_advertise[sizeof(DHCP6Message)];
>          uint16_t optcode;
> -        size_t optlen, len = sizeof(msg_advertise);
> +        size_t optlen, len = sizeof(msg_advertise) - sizeof(DHCP6Message);
>          be32_t val;
>          uint8_t preference = 255;
>          struct in6_addr addr;
> -- 
> 1.9.1
> 
>