Re: Crash noticed multiple times using libssh 0.3.4

[Aris Adamantiadis <aris@xxxxxxxxxxxx>]

I was too quick, I found the issue. I'll commit it in the 0.3 branch ASAP.

Aris

Aris Adamantiadis a écrit :
> Hello Uday,
> 
> I think I found the source of the problem. Somewhere in the
> enter_function() or leave_function(), a counter is underflowed (the
> current indentation level). Could you test the attached patch ? It
> doesn't resolve the indentation problem but stop it from crashing the
> process. Seeing your log, it seem the problem is in ssh_connect_host.
> 
> Thanks for your feedback, if the patch is helping, we'll commit it.
> 
> Regards,
> 
> Aris
> 
> Uday Tennety a écrit :
>> Hello Aris,
>> I made changes to our code and added mutex for the read and write blocks
>> for a particular session. During my testing, I still see the libssh
>> crashing at times. Also, I found that it always crashes at the following
>> location:
>> A call to the function ssh_log() is made from function ssh_connect in
>> client.c  Could it be that the session is getting corrupted at some
>> point? Can you give me some pointers looking at this Log.
>>
>> Thanks for your help.
>> Uday.
>>
>> t@133 (l@133) terminated by signal ABRT (Abort)
>> 0xff2c16e8: __lwp_kill+0x0008:  bcc,a,pt  %icc,__lwp_kill+0x18  !
>> 0xff2c16f8
>> Current function is ssh_log
>>   67         memset(indent, ' ', min);
>> --------------------------------------------------
>>
>> current thread: t@133
>>  [1] __lwp_kill(0x0, 0x6, 0x0, 0x6, 0xfc00, 0x0), at 0xff2c16e8
>>  [2] raise(0x6, 0x0, 0xff2a4d28, 0xffffffff, 0xff2e8298, 0x6), at
>> 0xff25ff38
>>  [3] abort(0x2d740, 0x1, 0xfeb00ab0, 0xa8244, 0xff2eb298, 0x0), at
>> 0xff240158
>>  [4] os::abort(0x1, 0xfedca58c, 0x1, 0xfedb2000, 0x1858c, 0x18400), at
>> 0xfeaf67b4
>>  [5] VMError::report_and_die(0xfeded4a8, 0x0, 0x1, 0xfed6095b,
>> 0xfed67006, 0xfedf2ce8), at 0xfec088d8
>>  [6] JVM_handle_solaris_signal(0xb, 0xdec7d670, 0xdec7d3b8, 0xafc00,
>> 0x0, 0x0), at 0xfe5b91e8
>>  [7] __sighndlr(0xb, 0xdec7d670, 0xdec7d3b8, 0xfe5b8724, 0x0, 0x1), at
>> 0xff2c0620
>>  ---- called from signal handler with signal 11 (SIGSEGV) ------
>>  [8] _memset(0xdec7d758, 0x20202020, 0xffffffd7, 0x17, 0xffffd740,
>> 0xdec80000), at 0xff351040
>> =>[9] ssh_log(session = 0x20202020, verbosity = 538976288, format =
>> 0x20202020 "<bad address 0x20202020>", ...), line 67 in "log.c"
>>  [10] ssh_connect(session = 0x20202020), line 510 in "client.c"
>>
>>
>>
>>
>>
>> Uday Tennety wrote:
>>> Hello Aris,
>>> Thanks for your inputs. I'll make the changes to my code adding mutex
>>> and let you know if I see any issues.
>>>
>>> Thanks,
>>> Uday.
>>>
>>> Aris Adamantiadis wrote:
>>>> ouch that reply-to catches me every time...
>>>>  
>>>> ------------------------------------------------------------------------
>>>>
>>>> Subject:
>>>> Re: [Fwd: Re: Crash noticed multiple times using libssh 0.3.4]
>>>> From:
>>>> Aris Adamantiadis <aris@xxxxxxxxxxxx>
>>>> Date:
>>>> Tue, 19 Jan 2010 09:56:01 +0100
>>>> To:
>>>> uday.tennety@xxxxxxxxxxxxxx
>>>>
>>>> To:
>>>> uday.tennety@xxxxxxxxxxxxxx
>>>>
>>>>
>>>> Uday Tennety a écrit :
>>>>  
>>>>> Hello Aris,
>>>>> I tried initialization using ssh_init() before calling any of the ssh
>>>>> functions but I still notice the crash. I've attached the relevant log
>>>>> statements. We're actually using one thread to read from the channel
>>>>> and
>>>>> another thread to write. Do you think this might be the reason for the
>>>>> crash? If so, what kind of workarounds do you recommend?
>>>>>
>>>>>     
>>>> Hi Uday,
>>>>
>>>> I still have to analyze the log you provided, but by what you describe,
>>>> the problem is that you're using two libssh function at same time on
>>>> functions that are not threadsafe on the same channel.
>>>>
>>>> I would recommend the use of a mutex in your own code, in order to
>>>> access only one libssh function at a time (at least on a single session,
>>>> there is normally no problem on different sessions).
>>>>
>>>> Do not hesitate to ask if you need any help.
>>>>
>>>> Regards,
>>>>
>>>> Aris
>>>>
>>>>   
> 

diff -ur libssh-0.3.4/include/libssh/priv.h libssh-0.3.4-patch/include/libssh/priv.h
--- libssh-0.3.4/include/libssh/priv.h	2009-09-14 19:02:27.000000000 +0200
+++ libssh-0.3.4-patch/include/libssh/priv.h	2010-01-26 13:37:37.000000000 +0100
@@ -238,7 +238,7 @@
 
 struct error_struct {
 /* error handling */
-    int error_code;
+    unsigned int error_code;
     char error_buffer[ERROR_BUFFERLEN];
 };
 
diff -ur libssh-0.3.4/libssh/connect.c libssh-0.3.4-patch/libssh/connect.c
--- libssh-0.3.4/libssh/connect.c	2009-09-14 19:02:27.000000000 +0200
+++ libssh-0.3.4-patch/libssh/connect.c	2010-01-26 13:43:04.000000000 +0100
@@ -246,7 +246,6 @@
       ssh_set_error(session, SSH_FATAL, "Connect failed: %s", strerror(errno));
       close(s);
       s = -1;
-      leave_function();
       continue;
     } else {
       /* We are connected */