[ovs-dev] [PATCH 1/1] stream_ssl: fix important memory leak in ssl_connect() function

William Tu u9012063 at gmail.com
Mon Sep 16 23:44:11 UTC 2019


On Mon, Sep 16, 2019 at 12:20 AM Damijan Skvarc <damjan.skvarc at gmail.com> wrote:
>
> Hi William and thanks for your review.
> I agree with your proposed changes.
> Is there still some action expected from me?
>
> thanks, Damijan

No, thanks for the patch.
Let's wait to see if others have more feedback.

William
>
>
>
> On Thu, Sep 12, 2019 at 8:00 PM William Tu <u9012063 at gmail.com> wrote:
>>
>> On Fri, Jul 26, 2019 at 10:11:03AM +0200, Damijan Skvarc wrote:
>> >
>> > While checking valgrind reports after running "make check-valgrind" I have noticed
>> > reports for several tests similar to the following:
>> >
>> > ....
>> > ==5345== Memcheck, a memory error detector
>> > ==5345== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
>> > ==5345== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
>> > ==5345== Command: ovsdb-client --private-key=/home/damijan.skvarc/doma/ovs/tests/testpki-privkey.pem --certificate=/home/damijan.skvarc/doma/ovs/tests/testpki-cert.pem --ca-cert=/home/damijan.skvarc/doma/ovs/tests/testpki-cacert.pem transact ssl:127.0.0.1:40111 \ \ \ ["ordinals",
>> > ==5345== \ \ \ \ \ \ {"op":\ "update",
>> > ==5345== \ \ \ \ \ \ \ "table":\ "ordinals",
>> > ==5345== \ \ \ \ \ \ \ "where":\ [["number",\ "==",\ 1]],
>> > ==5345== \ \ \ \ \ \ \ "row":\ {"number":\ 2,\ "name":\ "old\ two"}},
>> > ==5345== \ \ \ \ \ \ {"op":\ "update",
>> > ==5345== \ \ \ \ \ \ \ "table":\ "ordinals",
>> > ==5345== \ \ \ \ \ \ \ "where":\ [["name",\ "==",\ "two"]],
>> > ==5345== \ \ \ \ \ \ \ "row":\ {"number":\ 1,\ "name":\ "old\ one"}}]
>> > ==5345== Parent PID: 5344
>> > ==5345==
>> > ==5345==
>> > ==5345== HEAP SUMMARY:
>> > ==5345==     in use at exit: 116,551 bytes in 3,341 blocks
>> > ==5345==   total heap usage: 5,134 allocs, 1,793 frees, 412,290 bytes allocated
>> > ==5345==
>> > ==5345== 6,221 (184 direct, 6,037 indirect) bytes in 1 blocks are definitely lost in loss record 498 of 500
>> > ==5345==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> > ==5345==    by 0x5105E77: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5345==    by 0x51E1D23: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5345==    by 0x51E4861: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5345==    by 0x51E5414: ASN1_item_ex_d2i (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5345==    by 0x51E546A: ASN1_item_d2i (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5345==    by 0x4E56B27: ??? (in /lib/x86_64-linux-gnu/libssl.so.1.0.0)
>> > ==5345==    by 0x4E5BA11: ??? (in /lib/x86_64-linux-gnu/libssl.so.1.0.0)
>> > ==5345==    by 0x4E65145: ??? (in /lib/x86_64-linux-gnu/libssl.so.1.0.0)
>> > ==5345==    by 0x4522DF: ssl_connect (stream-ssl.c:530)
>> > ==5345==    by 0x443D38: scs_connecting (stream.c:315)
>> > ==5345==    by 0x443D38: stream_connect (stream.c:338)
>> > ==5345==    by 0x443FA1: stream_open_block (stream.c:266)
>> > ==5345==    by 0x40AB79: open_jsonrpc (ovsdb-client.c:507)
>> > ==5345==    by 0x40AB79: open_rpc (ovsdb-client.c:143)
>> > ==5345==    by 0x40B06B: do_transact__ (ovsdb-client.c:871)
>> > ==5345==    by 0x40B245: do_transact (ovsdb-client.c:893)
>> > ==5345==    by 0x405F76: main (ovsdb-client.c:282)
>> > ==5345==
>> > ==5345== LEAK SUMMARY:
>> > ==5345==    definitely lost: 184 bytes in 1 blocks
>> > ==5345==    indirectly lost: 6,037 bytes in 117 blocks
>> > ==5345==      possibly lost: 0 bytes in 0 blocks
>> > ==5345==    still reachable: 110,330 bytes in 3,223 blocks
>> > ==5345==         suppressed: 0 bytes in 0 blocks
>> > ==5345== Reachable blocks (those to which a pointer was found) are not shown.
>> > ==5345== To see them, rerun with: --leak-check=full --show-leak-kinds=all
>> > ==5345==
>> > ==5345== For counts of detected and suppressed errors, rerun with: -v
>> > ==5345== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
>> > ....
>> >
>> >
>> > This report was extracted from "index uniqueness checking" test and complains about
>> > leaking memory in ovsdb-client application. The problem is not huge, since ovsdb-client
>> > is CLI tool which is constantly reinvoked/restarted, thus leaked memory is not accumulated.
>> >
>> > More problematic issue is that for the same test valgrind reports the similar problem also for
>> > ovsdb-server:
>> >
>> > ....
>> > ==5290== Memcheck, a memory error detector
>> > ==5290== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
>> > ==5290== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
>> > ==5290== Command: ovsdb-server --log-file --detach --no-chdir --pidfile --private-key=/home/damijan.skvarc/doma/ovs/tests/testpki-privkey2.pem --certificate=/home/damijan.skvarc/doma/ovs/tests/testpki-cert2.pem --ca-cert=/home/damijan.skvarc/doma/ovs/tests/testpki-cacert.pem --remote=pssl:0:127.0.0.1 db
>> > ==5290== Parent PID: 5289
>> > ==5290==
>> > ==5292== Warning: noted but unhandled ioctl 0x2403 with no size/direction hints.
>> > ==5292==    This could cause spurious value errors to appear.
>> > ==5292==    See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a proper wrapper.
>> > ==5292== Warning: noted but unhandled ioctl 0x2400 with no size/direction hints.
>> > ==5292==    This could cause spurious value errors to appear.
>> > ==5292==    See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a proper wrapper.
>> > ==5290==
>> > ==5290== HEAP SUMMARY:
>> > ==5290==     in use at exit: 2,066 bytes in 48 blocks
>> > ==5290==   total heap usage: 87 allocs, 39 frees, 14,152 bytes allocated
>> > ==5290==
>> > ==5290== LEAK SUMMARY:
>> > ==5290==    definitely lost: 0 bytes in 0 blocks
>> > ==5290==    indirectly lost: 0 bytes in 0 blocks
>> > ==5290==      possibly lost: 0 bytes in 0 blocks
>> > ==5290==    still reachable: 2,066 bytes in 48 blocks
>> > ==5290==         suppressed: 0 bytes in 0 blocks
>> > ==5290== Reachable blocks (those to which a pointer was found) are not shown.
>> > ==5290== To see them, rerun with: --leak-check=full --show-leak-kinds=all
>> > ==5290==
>> > ==5290== For counts of detected and suppressed errors, rerun with: -v
>> > ==5290== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 1 from 1)
>> > ==5292== Warning: noted but unhandled ioctl 0x2401 with no size/direction hints.
>> > ==5292==    This could cause spurious value errors to appear.
>> > ==5292==    See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a proper wrapper.
>> > ==5292==
>> > ==5292== HEAP SUMMARY:
>> > ==5292==     in use at exit: 164,018 bytes in 4,252 blocks
>> > ==5292==   total heap usage: 17,910 allocs, 13,658 frees, 1,907,468 bytes allocated
>> > ==5292==
>> > ==5292== 49,720 (1,472 direct, 48,248 indirect) bytes in 8 blocks are definitely lost in loss record 580 of 580
>> > ==5292==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> > ==5292==    by 0x5105E77: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5292==    by 0x51E1D23: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5292==    by 0x51E4861: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5292==    by 0x51E5414: ASN1_item_ex_d2i (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5292==    by 0x51E546A: ASN1_item_d2i (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
>> > ==5292==    by 0x4E53E00: ??? (in /lib/x86_64-linux-gnu/libssl.so.1.0.0)
>> > ==5292==    by 0x4E55727: ??? (in /lib/x86_64-linux-gnu/libssl.so.1.0.0)
>> > ==5292==    by 0x452C4B: ssl_connect (stream-ssl.c:530)
>> > ==5292==    by 0x445B18: scs_connecting (stream.c:315)
>> > ==5292==    by 0x445B18: stream_connect (stream.c:338)
>> > ==5292==    by 0x445B91: stream_recv (stream.c:369)
>> > ==5292==    by 0x432A9C: jsonrpc_recv.part.7 (jsonrpc.c:310)
>> > ==5292==    by 0x433977: jsonrpc_recv (jsonrpc.c:1139)
>> > ==5292==    by 0x433977: jsonrpc_session_recv (jsonrpc.c:1112)
>> > ==5292==    by 0x40CCE3: ovsdb_jsonrpc_session_run (jsonrpc-server.c:553)
>> > ==5292==    by 0x40CCE3: ovsdb_jsonrpc_session_run_all (jsonrpc-server.c:586)
>> > ==5292==    by 0x40CCE3: ovsdb_jsonrpc_server_run (jsonrpc-server.c:401)
>> > ==5292==    by 0x40682E: main_loop (ovsdb-server.c:209)
>> > ==5292==    by 0x40682E: main (ovsdb-server.c:460)
>> > ==5292==
>> > ==5292== LEAK SUMMARY:
>> > ==5292==    definitely lost: 1,472 bytes in 8 blocks
>> > ==5292==    indirectly lost: 48,248 bytes in 936 blocks
>> > ==5292==      possibly lost: 0 bytes in 0 blocks
>> > ==5292==    still reachable: 114,298 bytes in 3,308 blocks
>> > ==5292==         suppressed: 0 bytes in 0 blocks
>> > ==5292== Reachable blocks (those to which a pointer was found) are not shown.
>> > ==5292== To see them, rerun with: --leak-check=full --show-leak-kinds=all
>> > ==5292==
>> > ==5292== For counts of detected and suppressed errors, rerun with: -v
>> > ==5292== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 1 from 1)
>> > ....
>> >
>> >
>> > In this case ovsdb-server is running as daemon process (--detach option) and leaking memory is
>> > accumulated whenever ovsdb-client is reconnected. Within observed test ovsdb-client CLI tool
>> > connects 8 times to ovsdb-server. Leaked memory in ovsdb-client (for each invocation) is approx.
>> > 6K bytes, while leaked memory in ovsdb-server is aprox. 48Kbytes what is actually 8*6K. Thus per
>> > each connection both ovsdb-client and ovsdb-server leak approx. 6K bytes.
>> >
>> > I have done a small manual test to check if ovsdb-server is indeed accumulating leaked memory
>> > by dumping ovsdb-server in a loop:
>> >
>> > console1:
>> > ovsdb-server \
>> > --log-file \
>> > --detach --no-chdir --pidfile \
>> > --private-key=testpki-privkey2.pem \
>> > --certificate=testpki-cert2.pem \
>> > --ca-cert=testpki-cacert.pem \
>> > --remote=pssl:0:127.0.0.1 \
>> > db
>> >
>> > while (true); do \
>> > ovsdb-client \
>> > --private-key=testpki-privkey.pem \
>> > --certificate=testpki-cert.pem \
>> > --ca-cert=testpki-cacert.pem \
>> > dump ssl:127.0.0.1:42067; \
>> > done
>> >
>> > console2:
>> > watch -n 0.5 'cat /proc/$(pidof ovsdb-server)/status | grep VmSize'
>> >
>> > In console2 it was evidently seen ovsdb-server is constantly leaking memory. After a while
>> > (i.e. after a certain number of reconnections) the OOM killer jumps out and kills ovsdb-server.
>> >
>> > Very similar situation was already noticed and described in
>> > https://github.com/openvswitch/ovs-issues/issues/168. There, the problem pops up while connecting
>> > controller to ovs-vswitchd daemon.
>> >
>> >
>> > Valgrind reports point to a problem in openssl library, however after studying openssl code for
>> > a while I have found out the problem is actually in ovs. When connection through SSL channel is
>> > taken place openssl library allocates memory for keeping track of certificate. Reference to this
>> > memory works very similar as std::shared_ptr pointer in recent C++ dialects. i.e. when allocated
>> > memory is referenced its reference counter is incremented and decremented after the memory is
>> > derefered. When reference counter becomes zero allocated memory is automatically deallocated.
>> >
>> > In openssl library environment certificate is retrieved by calling SSL_get_peer_certificate()
>> > where its reference counter is incremented. After retrieved certificate is not used any more its
>> > reference counter must be decremented by calling X509_free(). If not, allocated memory is never
>> > freed despite the ssl connection is properly closed.
>> >
>> > The problem was caused in stream-ssl.c in function ssl_connect(), which retrieves common peer name
>> > by calling SSL_get_peer_certificate() function and without calling X509_free() function afterwards.
>> >
>> >
>> > Signed-off-by: Damijan Skvarc <damjan.skvarc at gmail.com>
>> >
>> > ---
>> >  lib/stream-ssl.c | 7 ++++++-
>> >  1 file changed, 6 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/lib/stream-ssl.c b/lib/stream-ssl.c
>> > index 723fde9..231c362 100644
>> > --- a/lib/stream-ssl.c
>> > +++ b/lib/stream-ssl.c
>> > @@ -478,17 +478,20 @@ get_peer_common_name(const struct ssl_stream *sslv)
>> >      int cn_index = X509_NAME_get_index_by_NID(X509_get_subject_name(peer_cert),
>> >                                                NID_commonName, -1);
>> >      if (cn_index < 0) {
>> > +        X509_free(peer_cert);
>> >          return NULL;
>> >      }
>> >
>> >      X509_NAME_ENTRY *cn_entry = X509_NAME_get_entry(
>> >          X509_get_subject_name(peer_cert), cn_index);
>> >      if (!cn_entry) {
>> > +        X509_free(peer_cert);
>> >          return NULL;
>> >      }
>> >
>> >      ASN1_STRING *cn_data = X509_NAME_ENTRY_get_data(cn_entry);
>> >      if (!cn_data) {
>> > +        X509_free(peer_cert);
>> >          return NULL;
>> >      }
>> >
>> > @@ -499,7 +502,9 @@ get_peer_common_name(const struct ssl_stream *sslv)
>> >  #else
>> >      cn = (const char *)ASN1_STRING_get0_data(cn_data);
>> >   #endif
>> > -    return xstrdup(cn);
>> > +    char *p = xstrdup(cn);
>> > +    X509_free(peer_cert);
>> > +    return p;
>> >  }
>> >
>> >  static int
>>
>> Looks good to me.
>>
>> Thanks for the patch, maybe it's better avoiding duplicates of
>> X509_free by doing
>>
>> diff --git a/lib/stream-ssl.c b/lib/stream-ssl.c
>> index 723fde9ad8fe..078fcbc3aa4a 100644
>> --- a/lib/stream-ssl.c
>> +++ b/lib/stream-ssl.c
>> @@ -470,6 +470,7 @@ do_ca_cert_bootstrap(struct stream *stream)
>>  static char *
>>  get_peer_common_name(const struct ssl_stream *sslv)
>>  {
>> +    char *peer_name = NULL;
>>      X509 *peer_cert = SSL_get_peer_certificate(sslv->ssl);
>>      if (!peer_cert) {
>>          return NULL;
>> @@ -478,18 +479,18 @@ get_peer_common_name(const struct ssl_stream *sslv)
>>      int cn_index = X509_NAME_get_index_by_NID(X509_get_subject_name(peer_cert),
>>                                                NID_commonName, -1);
>>      if (cn_index < 0) {
>> -        return NULL;
>> +        goto error;
>>      }
>>
>>      X509_NAME_ENTRY *cn_entry = X509_NAME_get_entry(
>>          X509_get_subject_name(peer_cert), cn_index);
>>      if (!cn_entry) {
>> -        return NULL;
>> +        goto error;
>>      }
>>
>>      ASN1_STRING *cn_data = X509_NAME_ENTRY_get_data(cn_entry);
>>      if (!cn_data) {
>> -        return NULL;
>> +        goto error;
>>      }
>>
>>      const char *cn;
>> @@ -499,7 +500,11 @@ get_peer_common_name(const struct ssl_stream *sslv)
>>  #else
>>      cn = (const char *)ASN1_STRING_get0_data(cn_data);
>>   #endif
>> -    return xstrdup(cn);
>> +    peer_name = xstrdup(cn);
>> +
>> +error:
>> +    X509_free(peer_cert);
>> +    return peer_name;
>>  }
>>
>>  static int
>>
>>
>> Regards,
>> William
>>
>> > --
>> > 2.7.4
>> >
>> > _______________________________________________
>> > dev mailing list
>> > dev at openvswitch.org
>> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev


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