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Date: Thu, 12 Mar 2015 11:14:06 +0200
Message-ID: <CABBYNZKVUT2Z3L519iR09ZdT-m9dTHugUm2qaYwwJv-ZQ4f6yw@mail.gmail.com>
Subject: Re: [PATCH] core/gatt-database: Fix memory corruption
From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To: Andrejs Hanins <andrejs.hanins@ubnt.com>
Cc: Lukasz Rymanowski <lukasz.rymanowski@tieto.com>,
	Stefan Seyfried <stefan.seyfried@googlemail.com>,
	"linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Andrejs,

On Thu, Mar 12, 2015 at 10:54 AM, Andrejs Hanins
<andrejs.hanins@ubnt.com> wrote:
> Hi Luiz,
>
> On 2015.03.12. 10:39, Luiz Augusto von Dentz wrote:
>> Hi Andrejs,
>>
>> On Thu, Mar 12, 2015 at 10:24 AM, Andrejs Hanins
>> <andrejs.hanins@ubnt.com> wrote:
>>> Hi Lukasz,
>>>
>>> On 2015.03.11. 23:19, Stefan Seyfried wrote:
>>>> Am 11.03.2015 um 15:35 schrieb Andrejs Hanins:
>>>>> Pointer to on-stack variable was returned from pending_write_new.
>>>>
>>>> I still get a crash in the tests when running with memory debugging
>>>> enabled (which is default in openSUSE Build Service):
>>>>
>>>> $> MALLOC_CHECK_=3 MALLOC_PERTURB_=69 unit/test-gatt
>>>>
>>>> /TP/GAC/CL/BV-01-C - init
>>>> /TP/GAC/CL/BV-01-C - setup
>>>> [...]
>>>> /TP/GAR/CL/BV-01-C - setup complete
>>>> /TP/GAR/CL/BV-01-C - run
>>>> /TP/GAR/CL/BV-01-C - test passed
>>>> Segmentation fault
>>>>
>>>> Program received signal SIGSEGV, Segmentation fault.
>>>> 0x000055555558cb70 in bt_att_send (att=0x4000000f300432d, opcode=opcode@entry=24 '\030',
>>>>     pdu=pdu@entry=0x7fffffff4a0f, length=length@entry=1,
>>>>     callback=callback@entry=0x55555558fc30 <cancel_long_write_cb>, user_data=0x5555557b1ca0,
>>>>     destroy=destroy@entry=0x0) at src/shared/att.c:1135
>>>> 1135            if (!att || !att->io)
>>>> (gdb) bt
>>>> #0  0x000055555558cb70 in bt_att_send (att=0x4000000f300432d, opcode=opcode@entry=24 '\030',
>>>>     pdu=pdu@entry=0x7fffffff4a0f, length=length@entry=1,
>>>>     callback=callback@entry=0x55555558fc30 <cancel_long_write_cb>, user_data=0x5555557b1ca0,
>>>>     destroy=destroy@entry=0x0) at src/shared/att.c:1135
>>>> #1  0x0000555555591039 in cancel_long_write_req (client=<optimized out>, req=<optimized out>)
>>>>     at src/shared/gatt-client.c:1791
>>> Lukasz, I think there is some "missed-ref" problem related to the code you have recently added to the gatt-client/cancel_request() to cancel long_write and prep_write. Namely, bt_att_cancel can actually free the request which is later on accessed as req->long_write and req->prep_write thus reading free'd memory. Valgrind shows it happens this way:
>>>
>>>   Address 0x5a06fa8 is 8 bytes inside a block of size 40 free'd
>>>     at 0x4C2B200: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>>>     by 0x415BC0: request_unref (gatt-client.c:160)   <<------ this one frees the request which is accessed later in cancel_request()
>>>     by 0x410BB3: cancel_att_send_op (att.c:222)
>>>     by 0x412700: bt_att_cancel (att.c:1194)
>>>     by 0x418EC0: cancel_request (gatt-client.c:1852)
>>>     by 0x421C91: queue_remove_all (queue.c:387)
>>>     by 0x418F53: bt_gatt_client_cancel_all (gatt-client.c:1866)
>>>     by 0x418601: bt_gatt_client_free (gatt-client.c:1569)
>>>     by 0x418A65: bt_gatt_client_unref (gatt-client.c:1692)
>>>     by 0x4021FB: destroy_context (test-gatt.c:284)
>>>     by 0x40230C: context_quit (test-gatt.c:312)
>>>     by 0x4031AC: test_read_cb (test-gatt.c:677)
>>>
>>> I can't instantly figure out the proper fix (add_ref to the request in the beginning of cancel_request() to avoid preliminary free?), hopefully it will be easier for you, as you are the author of the original code. Probably there are also other similar issues elsewhere.
>>
>> Yep, this seems a regression we introduced with prepare write set, but
>> I did not managed to reproduce it with our unit tests how are getting
>> this trace?
>
> valgrind --log-file=valgrind.txt  ./unit/test-gatt
>
> But if you do "MALLOC_CHECK_=3 MALLOC_PERTURB_=69 unit/test-gatt" as suggested by Stefan, then core dump also happens to me.

Ive just sent a patch for it, it is not crashing even with the following:

MALLOC_CHECK_=3 MALLOC_PERTURB_=69 valgrind --trace-children=yes
--track-origins=yes --show-possibly-lost=no --leak-check=full
unit/test-gatt

==30730==
==30730== HEAP SUMMARY:
==30730==     in use at exit: 29,640 bytes in 618 blocks
==30730==   total heap usage: 36,559 allocs, 35,941 frees, 1,592,908
bytes allocated
==30730==
==30730== LEAK SUMMARY:
==30730==    definitely lost: 0 bytes in 0 blocks
==30730==    indirectly lost: 0 bytes in 0 blocks
==30730==      possibly lost: 0 bytes in 0 blocks
==30730==    still reachable: 29,640 bytes in 618 blocks
==30730==         suppressed: 0 bytes in 0 blocks

>
>>
>>>
>>>> #2  0x00005555555910ab in cancel_request (data=0x5555557b1e80) at src/shared/gatt-client.c:1855
>>>> #3  0x0000555555597903 in queue_remove_all (queue=<optimized out>, function=function@entry=0x0,
>>>>     user_data=user_data@entry=0x0, destroy=destroy@entry=0x555555591060 <cancel_request>)
>>>>     at src/shared/queue.c:387
>>>> #4  0x00005555555917cd in bt_gatt_client_cancel_all (client=client@entry=0x5555557b36f0)
>>>>     at src/shared/gatt-client.c:1866
>>>> #5  0x0000555555591839 in bt_gatt_client_free (client=0x5555557b36f0) at src/shared/gatt-client.c:1569
>>>> #6  0x0000555555589439 in destroy_context (context=0x5555557b1bb0) at unit/test-gatt.c:284
>>>> #7  context_quit (user_data=0x5555557b1bb0) at unit/test-gatt.c:312
>>>> #8  0x000055555558d59b in handle_rsp (pdu_len=<optimized out>, pdu=0x5555557c6571 "\001\002\003\001)",
>>>>     opcode=11 '\v', att=0x5555557b2e90) at src/shared/att.c:640
>>>> #9  can_read_data (io=<optimized out>, user_data=0x5555557b2e90) at src/shared/att.c:813
>>>> #10 0x0000555555596ec5 in watch_callback (channel=<optimized out>, cond=<optimized out>,
>>>>     user_data=<optimized out>) at src/shared/io-glib.c:170
>>>> #11 0x00007ffff7b198e5 in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0
>>>> #12 0x00007ffff7b19c48 in ?? () from /usr/lib64/libglib-2.0.so.0
>>>> #13 0x00007ffff7b19f0a in g_main_loop_run () from /usr/lib64/libglib-2.0.so.0
>>>> #14 0x000055555558c031 in tester_run () at src/shared/tester.c:830
>>>> #15 0x0000555555587e19 in main (argc=1, argv=0x7fffffffdc58) at unit/test-gatt.c:3182
>>>>
>>>> Valgrind also complains loudly:
>>>> $> valgrind unit/test-gatt > /dev/null
>>>> ==20817== Memcheck, a memory error detector
>>>> ==20817== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
>>>> ==20817== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
>>>> ==20817== Command: unit/test-gatt
>>>> ==20817==
>>>> ==20817== Syscall param socketcall.bind(my_addr.sa_data) points to uninitialised byte(s)
>>>> ==20817==    at 0x522A737: bind (in /lib64/libc-2.21.so)
>>>> ==20817==    by 0x14BBC2: ecb_aes_setup (crypto.c:110)
>>>> ==20817==    by 0x14BBC2: bt_crypto_new (crypto.c:148)
>>>> ==20817==    by 0x140788: bt_att_new (att.c:937)
>>>> ==20817==    by 0x13EA4B: create_context.constprop.24 (test-gatt.c:592)
>>>> ==20817==    by 0x13F2E2: run_callback (tester.c:412)
>>>> ==20817==    by 0x4E808E4: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80C47: ??? (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80F09: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x140030: tester_run (tester.c:830)
>>>> ==20817==    by 0x13BE18: main (test-gatt.c:3182)
>>>> ==20817==  Address 0xffeff6aa8 is on thread 1's stack
>>>> ==20817==  in frame #1, created by bt_crypto_new (crypto.c:141)
>>>> ==20817==
>>> This one looks like a Valgrind bug. It probably does not take into account, that sockaddr passed to the bind is not a 'struct sockaddr' but actually a 'struct sockaddr_alg' of different size. The code, as such, does proper initialization.
>>
>> Valgrind probably is expecting some other size for the sockaddr, we do
>> memset to 0 so it is probably just a false positive.
>>
>>>> ==20817== Syscall param socketcall.bind(my_addr.sa_data) points to uninitialised byte(s)
>>>> ==20817==    at 0x522A737: bind (in /lib64/libc-2.21.so)
>>>> ==20817==    by 0x14BC4B: cmac_aes_setup (crypto.c:132)
>>>> ==20817==    by 0x14BC4B: bt_crypto_new (crypto.c:161)
>>>> ==20817==    by 0x140788: bt_att_new (att.c:937)
>>>> ==20817==    by 0x13EA4B: create_context.constprop.24 (test-gatt.c:592)
>>>> ==20817==    by 0x13F2E2: run_callback (tester.c:412)
>>>> ==20817==    by 0x4E808E4: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80C47: ??? (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80F09: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x140030: tester_run (tester.c:830)
>>>> ==20817==    by 0x13BE18: main (test-gatt.c:3182)
>>>> ==20817==  Address 0xffeff6aa8 is on thread 1's stack
>>>> ==20817==  in frame #1, created by bt_crypto_new (crypto.c:141)
>>>> ==20817==
>>>> ==20817== Invalid read of size 1
>>>> ==20817==    at 0x145076: cancel_request (gatt-client.c:1854)
>>>> ==20817==    by 0x14B902: queue_remove_all (queue.c:387)
>>>> ==20817==    by 0x1457CC: bt_gatt_client_cancel_all (gatt-client.c:1866)
>>>> ==20817==    by 0x145838: bt_gatt_client_free (gatt-client.c:1569)
>>>> ==20817==    by 0x13D438: destroy_context (test-gatt.c:284)
>>>> ==20817==    by 0x13D438: context_quit (test-gatt.c:312)
>>>> ==20817==    by 0x14159A: handle_rsp (att.c:640)
>>>> ==20817==    by 0x14159A: can_read_data (att.c:813)
>>>> ==20817==    by 0x14AEC4: watch_callback (io-glib.c:170)
>>>> ==20817==    by 0x4E808E4: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80C47: ??? (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80F09: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x140030: tester_run (tester.c:830)
>>>> ==20817==    by 0x13BE18: main (test-gatt.c:3182)
>>>> ==20817==  Address 0x5a13908 is 8 bytes inside a block of size 40 free'd
>>>> ==20817==    at 0x4C2A37C: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
>>>> ==20817==    by 0x140F1E: cancel_att_send_op (att.c:222)
>>>> ==20817==    by 0x140F1E: bt_att_cancel (att.c:1200)
>>>> ==20817==    by 0x145075: cancel_request (gatt-client.c:1852)
>>>> ==20817==    by 0x14B902: queue_remove_all (queue.c:387)
>>>> ==20817==    by 0x1457CC: bt_gatt_client_cancel_all (gatt-client.c:1866)
>>>> ==20817==    by 0x145838: bt_gatt_client_free (gatt-client.c:1569)
>>>> ==20817==    by 0x13D438: destroy_context (test-gatt.c:284)
>>>> ==20817==    by 0x13D438: context_quit (test-gatt.c:312)
>>>> ==20817==    by 0x14159A: handle_rsp (att.c:640)
>>>> ==20817==    by 0x14159A: can_read_data (att.c:813)
>>>> ==20817==    by 0x14AEC4: watch_callback (io-glib.c:170)
>>>> ==20817==    by 0x4E808E4: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80C47: ??? (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80F09: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==
>>>> ==20817== Invalid read of size 1
>>>> ==20817==    at 0x14507C: cancel_request (gatt-client.c:1857)
>>>> ==20817==    by 0x14B902: queue_remove_all (queue.c:387)
>>>> ==20817==    by 0x1457CC: bt_gatt_client_cancel_all (gatt-client.c:1866)
>>>> ==20817==    by 0x145838: bt_gatt_client_free (gatt-client.c:1569)
>>>> ==20817==    by 0x13D438: destroy_context (test-gatt.c:284)
>>>> ==20817==    by 0x13D438: context_quit (test-gatt.c:312)
>>>> ==20817==    by 0x14159A: handle_rsp (att.c:640)
>>>> ==20817==    by 0x14159A: can_read_data (att.c:813)
>>>> ==20817==    by 0x14AEC4: watch_callback (io-glib.c:170)
>>>> ==20817==    by 0x4E808E4: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80C47: ??? (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80F09: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x140030: tester_run (tester.c:830)
>>>> ==20817==    by 0x13BE18: main (test-gatt.c:3182)
>>>> ==20817==  Address 0x5a13909 is 9 bytes inside a block of size 40 free'd
>>>> ==20817==    at 0x4C2A37C: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
>>>> ==20817==    by 0x140F1E: cancel_att_send_op (att.c:222)
>>>> ==20817==    by 0x140F1E: bt_att_cancel (att.c:1200)
>>>> ==20817==    by 0x145075: cancel_request (gatt-client.c:1852)
>>>> ==20817==    by 0x14B902: queue_remove_all (queue.c:387)
>>>> ==20817==    by 0x1457CC: bt_gatt_client_cancel_all (gatt-client.c:1866)
>>>> ==20817==    by 0x145838: bt_gatt_client_free (gatt-client.c:1569)
>>>> ==20817==    by 0x13D438: destroy_context (test-gatt.c:284)
>>>> ==20817==    by 0x13D438: context_quit (test-gatt.c:312)
>>>> ==20817==    by 0x14159A: handle_rsp (att.c:640)
>>>> ==20817==    by 0x14159A: can_read_data (att.c:813)
>>>> ==20817==    by 0x14AEC4: watch_callback (io-glib.c:170)
>>>> ==20817==    by 0x4E808E4: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80C47: ??? (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==    by 0x4E80F09: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.1)
>>>> ==20817==
>>>> ==20817==
>>>> ==20817== HEAP SUMMARY:
>>>> ==20817==     in use at exit: 29,640 bytes in 618 blocks
>>>> ==20817==   total heap usage: 36,545 allocs, 35,927 frees, 1,585,464 bytes allocated
>>>> ==20817==
>>>> ==20817== LEAK SUMMARY:
>>>> ==20817==    definitely lost: 0 bytes in 0 blocks
>>>> ==20817==    indirectly lost: 0 bytes in 0 blocks
>>>> ==20817==      possibly lost: 0 bytes in 0 blocks
>>>> ==20817==    still reachable: 29,640 bytes in 618 blocks
>>>> ==20817==         suppressed: 0 bytes in 0 blocks
>>>> ==20817== Rerun with --leak-check=full to see details of leaked memory
>>>> ==20817==
>>>> ==20817== For counts of detected and suppressed errors, rerun with: -v
>>>> ==20817== Use --track-origins=yes to see where uninitialised values come from
>>>> ==20817== ERROR SUMMARY: 358 errors from 4 contexts (suppressed: 0 from 0)
>>>>
>>>> Unfortunately, my understanding of the code did not allow me
>>>> to fis this :-(
>>>>
>>>> Best regards,
>>>>
>>>>       Stefan
>>>>
>>
>>
>>



-- 
Luiz Augusto von Dentz