2.2.0 crash at a strange location

Stefan Winter stefan.winter at restena.lu
Mon May 6 11:59:36 CEST 2013


Hi,

gettings closer...

I set a breakpoint into normify() and checked what it does right before the memcpy:

Breakpoint 1, normify (request=request at entry=0x1241a00, vp=vp at entry=0x1242f00, min_length=min_length at entry=20)
    at rlm_pap.c:246
246     {
(gdb) print vp
$1 = (VALUE_PAIR *) 0x1242f00
(gdb) print *vp
$2 = {name = 0x1060150 "SSHA1-Password", attribute = 1094, vendor = 0, type = 5, length = 36, 
  operator = T_OP_SET, flags = {addport = 0, has_tag = 0, do_xlat = 0, unknown_attr = 0, array = 0, 
    has_value = 0, has_value_alias = 0, has_tlv = 0, is_tlv = 0, encoded = 0, tag = 0 '\000', 
    encrypt = 0 '\000'}, next = 0x1242490, lvalue = 0, data = {
    strvalue = "=\\*\276\232\250\311\000@\b\261\067\067\031\066\"\332\003\217\035QOrr*oRvDSoZ9i%&dkRTb1o5aSUm", '\000' <repeats 205 times>, 
    octets = "=\\*\276\232\250\311\000@\b\261\067\067\031\066\"\332\003\217\035QOrr*oRvDSoZ9i%&dkRTb1o5aSUm", '\000' <repeats 205 times>, ipaddr = {s_addr = 3190447165}, ipv6addr = {__in6_u = {
        __u6_addr8 = "=\\*\276\232\250\311\000@\b\261\067\067\031\066\"", __u6_addr16 = {23613, 48682, 43162, 
          201, 2112, 14257, 6455, 8758}, __u6_addr32 = {3190447165, 13215898, 934348864, 573970743}}}, 
    date = 3190447165, integer = 3190447165, sinteger = -1104520131, 
    filter = "=\\*\276\232\250\311\000@\b\261\067\067\031\066\"\332\003\217\035QOrr*oRvDSoZ", 
    ifid = "=\\*\276\232\250", <incomplete sequence \311>, 
    ipv6prefix = "=\\*\276\232\250\311\000@\b\261\067\067\031\066\"\332\003", ether = "=\\*\276\232\250", 
    tlv = 0xc9a89abe2a5c3d <Address 0xc9a89abe2a5c3d out of bounds>}}
(gdb)

( ... step/next until memcpy ... )

272                             RDEBUG2("Normalizing %s from base64 encoding", vp->name);
(gdb) next
273                             memcpy(vp->vp_octets, buffer, decoded);

(gdb) print buffer
$8 = "Гp  {...}\000h_debugfallback {...}\000\026C", '\000' <repeats 28 times>, " "

And there is a suymptom of the problem! The hash

PVwqvpqoyQBACLE3Nxk2ItoDjx1RT3JyKm9SdkRTb1o5aSUm

decodes as

=\*�����776"��QOrr*oRvDSoZ9i%&

on my cmdline; i.e. it at least starts with equals-backslash-star.

The buffer line doesn't. It suspciously contains parts of my config (parts of the "pap_hash_debugfallback" string). So I guess the problem is indeed inside the preceding base64_decode.

I'll be step'ing into it to see where it goes wrong... which might be ugly.

Stefan

On 06.05.2013 11:28, Stefan Winter wrote:
> Hi one more time,
> 
> and another update: it's one specific SSHA1-Hash which makes the server crash; I can reproduce this easily.
> 
> The magic hash value is:
> 
> SSHA1-Password := PVwqvpqoyQBACLE3Nxk2ItoDjx1RT3JyKm9SdkRTb1o5aSUm
> 
> and makes things fail specifically during a memcpy inside normify().
> Below is what valgrind has to say. Note that the user input in 
> User-Password is irrelevant; failure is before it's even checked.
> 
> HTH,
> 
> Stefan
> 
> Found Auth-Type = PAP
> # Executing group from file /usr/local/freeradius/config/raddb/sites-enabled/SMTP
> +- entering group PAP {...}
> ++- entering policy pap_hash_debugfallback {...}
> +++- entering group  {...}
> [pap] login attempt with password "foopass"
> [pap] Using SSHA encryption.
> [pap] Normalizing SSHA1-Password from base64 encoding
> ==13555== 
> ==13555== Process terminating with default action of signal 11 (SIGSEGV)
> ==13555==  Access not within mapped region at address 0x7FF001000
> ==13555==    at 0x4C2C476: memcpy@@GLIBC_2.14 (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==13555==    by 0x874B643: normify (rlm_pap.c:273)
> ==13555==    by 0x874BDDF: pap_authenticate (rlm_pap.c:707)
> ==13555==    by 0x41D764: modcall (modcall.c:304)
> ==13555==    by 0x41BF38: indexed_modcall (modules.c:740)
> ==13555==    by 0x40B176: rad_authenticate (auth.c:382)
> ==13555==    by 0x4296E4: radius_handle_request (event.c:3784)
> ==13555==    by 0x422227: thread_pool_addrequest (threads.c:887)
> ==13555==    by 0x4272E5: event_socket_handler (event.c:3429)
> ==13555==    by 0x4E4A2B4: fr_event_loop (event.c:415)
> ==13555==    by 0x409F53: main (radiusd.c:408)
> ==13555==  If you believe this happened as a result of a stack
> ==13555==  overflow in your program's main thread (unlikely but
> ==13555==  possible), you can try to increase the size of the
> ==13555==  main thread stack using the --main-stacksize= flag.
> ==13555==  The main thread stack size used in this run was 8388608.
> ==13555== 
> ==13555== ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ---- --13555-- VALGRIND INTERNAL ERROR: Valgrind received a signal 11 (SIGSEGV) - exiting
> --13555-- si_code=1;  Faulting address: 0xC2394B0;  sp: 0x402bda060
> 
> valgrind: the 'impossible' happened:
>    Killed by fatal signal
> ==13555==    at 0x38057958: ??? (in /usr/lib64/valgrind/memcheck-amd64-linux)
> ==13555==    by 0x3802124C: ??? (in /usr/lib64/valgrind/memcheck-amd64-linux)
> ==13555==    by 0x380213DA: ??? (in /usr/lib64/valgrind/memcheck-amd64-linux)
> ==13555==    by 0x3808F8D4: ??? (in /usr/lib64/valgrind/memcheck-amd64-linux)
> ==13555==    by 0x380551FF: ??? (in /usr/lib64/valgrind/memcheck-amd64-linux)
> ==13555==    by 0x38055304: ??? (in /usr/lib64/valgrind/memcheck-amd64-linux)
> ==13555==    by 0x3809EA61: ??? (in /usr/lib64/valgrind/memcheck-amd64-linux)
> 
> sched status:
>   running_tid=1
> 
> Thread 1: status = VgTs_Runnable
> ==13555==    at 0x4C2ABED: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==13555==    by 0x4013B76: _dl_close_worker (in /lib64/ld-2.15.so)
> ==13555==    by 0x40140AB: _dl_close (in /lib64/ld-2.15.so)
> ==13555==    by 0x400E5F5: _dl_catch_error (in /lib64/ld-2.15.so)
> ==13555==    by 0x64543CE: dlerror_run (in /lib64/libc-2.15.so)
> ==13555==    by 0x6485946: free_mem (in /lib64/libc-2.15.so)
> ==13555==    by 0x6485691: __libc_freeres (in /lib64/libc-2.15.so)
> ==13555==    by 0x4A246EC: _vgnU_freeres (in /usr/lib64/valgrind/vgpreload_core-amd64-linux.so)
> ==13555==    by 0x801604F: ???
> ==13555==    by 0x874B643: normify (rlm_pap.c:273)
> ==13555==    by 0x874BDDF: pap_authenticate (rlm_pap.c:707)
> ==13555==    by 0x41D764: modcall (modcall.c:304)
> ==13555==    by 0x41BF38: indexed_modcall (modules.c:740)
> ==13555==    by 0x40B176: rad_authenticate (auth.c:382)
> ==13555==    by 0x4296E4: radius_handle_request (event.c:3784)
> ==13555==    by 0x422227: thread_pool_addrequest (threads.c:887)
> ==13555==    by 0x4272E5: event_socket_handler (event.c:3429)
> ==13555==    by 0x4E4A2B4: fr_event_loop (event.c:415)
> ==13555==    by 0x409F53: main (radiusd.c:408)
> 
> 
> Note: see also the FAQ in the source distribution.
> It contains workarounds to several common problems.
> In particular, if Valgrind aborted or crashed after
> identifying problems in your program, there's a good chance
> that fixing those problems will prevent Valgrind aborting or
> crashing, especially if it happened in m_mallocfree.c.
> 
> If that doesn't help, please report this bug to: www.valgrind.org
> 
> In the bug report, send all the above text, the valgrind
> version, and what OS and version you are using.  Thanks.
> 
> On 06.05.2013 10:48, Stefan Winter wrote:
>> Hi again,
>>
>> running with -X I get:
>>
>> rlm_sql_mysql: query:  (SELECT id, username, attribute, value, op FROM check_smtp_ssha1 WHERE username='someusername')
>> [sql-smtp-hash] User found in radcheck table
>> rlm_sql (sql-smtp-hash): Released sql socket id: 1
>> +++[sql-smtp-hash] returns ok
>> ++- policy redundant returns ok
>> [pap] Normalizing SSHA1-Password from base64 encoding
>> ++[pap] returns updated
>> Found Auth-Type = PAP
>> # Executing group from file /usr/local/freeradius/config/raddb/sites-enabled/SMTP
>> +- entering group PAP {...}
>> ++- entering policy pap_hash_debugfallback {...}
>> +++- entering group  {...}
>> [pap] login attempt with password "eq346ici"
>> [pap] Using SSHA encryption.
>> [pap] Normalizing SSHA1-Password from base64 encoding
>> Segmentation fault
>>
>> Which is before the linelog is reached, so *maybe* the source of the problem is in the base64 normalisation code?
>>
>> Stefan
>>
>> On 06.05.2013 10:30, Stefan Winter wrote:
>>> Hi,
>>>
>>> today I did some minor config changes which turned my stable-running
>>> 2.2.0 into a crash-every-5-min server :-(
>>>
>>> The change involved 
>>> a) switching from Cleartext-Password to SSHA1-Password (retaining the
>>>    pap module for checking the PW validity)
>>> b) a somewhat sophisticated unlang statement to express: if the SSHA1-PW
>>>    was wrong, retrieve an alternative password from a VSA 
>>>    ("RESTENA-Debug-Password") and set it to be the Cleartext-Password;
>>>    then try pap again with that
>>>
>>> This is obviously the implementation of a "backdoor" for our helpdesk
>>> if we need to login into a user's account for debugging without knowing
>>> his actual password because it's SSHA'ed in the DB.
>>>
>>> All nice and cute, and it worked while doing "mild" usage with a test
>>> account - but now in production things go down the drain with it.
>>>
>>> I've temporarily switched back to the previous SQL query which had
>>> Cleartext-Password. And voilà: the server is stable again. Even with
>>> the unlang construct still in place (below for reference).
>>>
>>> So I strongly suspect things to go wrong *only if* SSHA1-Passwords
>>> are used to authenticate the user. 
>>>
>>> Strangely enough, the gdb backtrace shows that it fails somewhere inside
>>> glibc while trying to expand a %S in xlat - which appears totally
>>> unrelated to the changes I did. The backtrace is below.
>>>
>>> policy.conf: replacement for authenticate/pap:
>>>
>>> policy {
>>>
>>>         pap_hash_debugfallback {
>>>                 group {
>>>                         pap {
>>>                                 reject = 2
>>>                                 ok = return
>>>                         }
>>>
>>>                         if ( "%{control:RESTENA-Debug-Password}" ) {
>>>                                 update control {
>>>                                         SSHA1-Password !* "nogood"
>>>                                         NT-Password !* "nogood"
>>>                                         Cleartext-Password := "%{control:RESTENA-Debug-Password}"
>>>                                 }
>>>                                 ok = 1 
>>>                                 ok
>>>                         }
>>>                         
>>>                         pap {
>>>                                 reject = 2
>>>                                 ok = return
>>>                         }
>>>                 }
>>>         }
>>> ...
>>> }
>>>
>>>
>>> Program received signal SIGSEGV, Segmentation fault.
>>> [Switching to Thread 0x4b015950 (LWP 24837)]
>>> 0x00002b380d7d5550 in ?? () from /lib64/libc.so.6
>>> (gdb) bt
>>> #0  0x00002b380d7d5550 in ?? () from /lib64/libc.so.6
>>> #1  0x00002b380d7d6c0c in malloc () from /lib64/libc.so.6
>>> #2  0x00002b380d7da8f2 in strdup () from /lib64/libc.so.6
>>> #3  0x00002b380d7ed928 in ?? () from /lib64/libc.so.6
>>> #4  0x00002b380d7ee3f0 in tzset () from /lib64/libc.so.6
>>> #5  0x00002b380d7f2c94 in strftime_l () from /lib64/libc.so.6
>>> #6  0x000000000042277d in radius_xlat (out=0x4b013a30 "[Access-Accept", outlen=1023, fmt=0x667c4e "[%S] [AUTH OK   ] '%{User-Name}' (%{RESTENA-Service-Type}:%{client:shortname})", request=0x2aaab0001f60, 
>>>     func=0x2aaaab2e33d0 <linelog_escape_func>) at xlat.c:1348
>>> #7  0x00002aaaab2e31d4 in do_linelog (instance=0x835a60, request=0x2aaab0001f60) at rlm_linelog.c:328
>>> #8  0x000000000041c920 in modcall (component=7, c=<value optimized out>, request=0x2aaab0001f60) at modcall.c:304
>>> #9  0x0000000000419be8 in indexed_modcall (comp=0, idx=0, request=0x2aaab0001f60) at modules.c:740
>>> #10 0x00000000004094fd in rad_postauth (request=0x2aaab0001f60) at auth.c:433
>>> #11 0x0000000000409b83 in rad_authenticate (request=0x2aaab0001f60) at auth.c:831
>>> #12 0x0000000000427538 in radius_handle_request (request=0x2aaab0001f60, fun=0x409540 <rad_authenticate>) at event.c:3784
>>> #13 0x0000000000420728 in request_handler_thread (arg=<value optimized out>) at threads.c:537
>>> #14 0x00002b380c8d8020 in start_thread () from /lib64/libpthread.so.0
>>> #15 0x00002b380d829f8d in clone () from /lib64/libc.so.6
>>> #16 0x0000000000000000 in ?? ()
>>> (gdb) bt full
>>> #0  0x00002b380d7d5550 in ?? () from /lib64/libc.so.6
>>> No symbol table info available.
>>> #1  0x00002b380d7d6c0c in malloc () from /lib64/libc.so.6
>>> No symbol table info available.
>>> #2  0x00002b380d7da8f2 in strdup () from /lib64/libc.so.6
>>> No symbol table info available.
>>> #3  0x00002b380d7ed928 in ?? () from /lib64/libc.so.6
>>> No symbol table info available.
>>> #4  0x00002b380d7ee3f0 in tzset () from /lib64/libc.so.6
>>> No symbol table info available.
>>> #5  0x00002b380d7f2c94 in strftime_l () from /lib64/libc.so.6
>>> No symbol table info available.
>>> #6  0x000000000042277d in radius_xlat (out=0x4b013a30 "[Access-Accept", outlen=1023, fmt=0x667c4e "[%S] [AUTH OK   ] '%{User-Name}' (%{RESTENA-Service-Type}:%{client:shortname})", request=0x2aaab0001f60, 
>>>     func=0x2aaaab2e33d0 <linelog_escape_func>) at xlat.c:1348
>>>         c = <value optimized out>
>>>         len = <value optimized out>
>>>         freespace = <value optimized out>
>>>         p = 0x667c50 "S] [AUTH OK   ] '%{User-Name}' (%{RESTENA-Service-Type}:%{client:shortname})"
>>>         q = 0x4b013a31 "Access-Accept"
>>>         tmp = (VALUE_PAIR *) 0x2aaab0001f60
>>>         TM = (struct tm *) 0x3
>>>         s_TM = {tm_sec = 45, tm_min = 15, tm_hour = 10, tm_mday = 6, tm_mon = 4, tm_year = 113, tm_wday = 1, tm_yday = 125, tm_isdst = 1, tm_gmtoff = 7200, tm_zone = 0x807da0 "CEST"}
>>>         tmpdt = "\000\020\000\000\000\000\000\000\000\020\000\000\000\000\000\000\b\000\000\000\000\000\000\000\236A�G", '\0' <repeats 11 times>
>>> #7  0x00002aaaab2e31d4 in do_linelog (instance=0x835a60, request=0x2aaab0001f60) at rlm_linelog.c:328
>>>         ci = <value optimized out>
>>>         cp = <value optimized out>
>>>         fd = 56
>>>         buffer = "/var/log/radius/activity.log\000+\000\000�*\001K\001\000\000\000�+\001K\000\000\000\000�X\001K\000\000\000\000\000�\213\000\000\000\000\000\005\000\000\000\000\000\000\000�>\000��*\000\000\000\000\000\000\000\000\000\000�>\000��*\000\000\n\000\000\000\000\000\000\000�>\000��*\000\000P>\001K\000\000\000\000�w�\0178+\000\000:=\000\000\000\000\000\000\030", '\0' <repeats 15 times>, "�\025B\000\000\000\000\000\000�\213\000\000\000\000\000�*\001K\000\000\000\000P>\001K\000\000\000\000`\037\000��*\000\000\000\000\002\000\000\000\000\000\220�\213\000\000"...
>>>         p = <value optimized out>
>>>         line = "[Access-Accept", '\0' <repeats 434 times>, "Mon May  6 10:15:45 2013\000\000\000\000\000\000\000\000Mon May  6 10:15:45 2013", '\0' <repeats 116 times>, "\024\000\000\000`\001\000\000\000\000\000\0008\001\000\000\000\000\000\000\000\000\000\000\024", '\0' <repeats 35 times>, "\202\230'\f8+\000\000`\003j\000\000\000\000\000 \000\000��*\000\0008\001", '\0' <repeats 14 times>, "\001\000\000\000\000\000\000\000`\037\000��*\000\0000}\203\000\000\000\000\000\fl}\r8+\000\000�\204|", '\0' <repeats 13 times>...
>>>         value = 0x667c4e "[%S] [AUTH OK   ] '%{User-Name}' (%{RESTENA-Service-Type}:%{client:shortname})"
>>>         gid = <value optimized out>
>>>         grp = (struct group *) 0x0
>>>         endptr = 0x6889fc ")"
>>> #8  0x000000000041c920 in modcall (component=7, c=<value optimized out>, request=0x2aaab0001f60) at modcall.c:304
>>>         server = <value optimized out>
>>>         myresult = 1
>>>         stack = {pointer = 0, priority = {0, 0, 3, 0, 0, 0, 0, 0, 0, 3, 0, 3, 0 <repeats 20 times>}, result = {7, 7, 2, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 0 <repeats 19 times>}, children = {0x8f2910, 0x8f2730, 0x8f2800, 0x0, 
>>>     0x837410, 0x0 <repeats 27 times>}, start = {0x0, 0x8f2730, 0x8f27a0, 0x0, 0x0, 0x837480, 0x8374f0, 0x8af080, 0x8e3ec0, 0x0 <repeats 23 times>}}
>>>         parent = (modcallable *) 0x8f2730
>>>         child = (modcallable *) 0x8f2800
>>>         if_taken = 0
>>>         was_if = 0
>>> #9  0x0000000000419be8 in indexed_modcall (comp=0, idx=0, request=0x2aaab0001f60) at modules.c:740
>>>         this = <value optimized out>
>>>         rcode = <value optimized out>
>>>         list = (modcallable *) 0x8f2910
>>>         server = (virtual_server_t *) 0x837330
>>> #10 0x00000000004094fd in rad_postauth (request=0x2aaab0001f60) at auth.c:433
>>>         result = <value optimized out>
>>>         postauth_type = 0
>>>         vp = (VALUE_PAIR *) 0x0
>>> #11 0x0000000000409b83 in rad_authenticate (request=0x2aaab0001f60) at auth.c:831
>>>         namepair = (VALUE_PAIR *) 0x9a71f0
>>>         check_item = (VALUE_PAIR *) 0x0
>>>         auth_item = (VALUE_PAIR *) 0x9a8c10
>>>         module_msg = <value optimized out>
>>>         tmp = (VALUE_PAIR *) 0x0
>>>         result = -1275060192
>>>         autz_retry = <value optimized out>
>>>         autz_type = <value optimized out>
>>> #12 0x0000000000427538 in radius_handle_request (request=0x2aaab0001f60, fun=0x409540 <rad_authenticate>) at event.c:3784
>>> ---Type <return> to continue, or q <return> to quit---
>>> No locals.
>>> #13 0x0000000000420728 in request_handler_thread (arg=<value optimized out>) at threads.c:537
>>>         fun = (RAD_REQUEST_FUNP) 0x409540 <rad_authenticate>
>>>         self = (THREAD_HANDLE *) 0x2aaab4001fe0
>>> #14 0x00002b380c8d8020 in start_thread () from /lib64/libpthread.so.0
>>> No symbol table info available.
>>> #15 0x00002b380d829f8d in clone () from /lib64/libc.so.6
>>> No symbol table info available.
>>> #16 0x0000000000000000 in ?? ()
>>> No symbol table info available.
>>> (gdb)
>>>
>>>
>>>
>>> -
>>> List info/subscribe/unsubscribe? See http://www.freeradius.org/list/devel.html
>>>
>>
>>
>>
>>
>> -
>> List info/subscribe/unsubscribe? See http://www.freeradius.org/list/devel.html
>>
> 
> 
> 
> 
> -
> List info/subscribe/unsubscribe? See http://www.freeradius.org/list/devel.html
> 


-- 
Stefan WINTER
Ingenieur de Recherche
Fondation RESTENA - Réseau Téléinformatique de l'Education Nationale et de la Recherche
6, rue Richard Coudenhove-Kalergi
L-1359 Luxembourg

Tel: +352 424409 1
Fax: +352 422473

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