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https://issues.apache.org/activemq/browse/AMQCPP-178?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Timothy Bish reassigned AMQCPP-178:
-----------------------------------
Assignee: Timothy Bish (was: Nathan Mittler)
> Core dump in ActiveMQException::buildMessage
> --------------------------------------------
>
> Key: AMQCPP-178
> URL: https://issues.apache.org/activemq/browse/AMQCPP-178
> Project: ActiveMQ C++ Client
> Issue Type: Bug
> Components: CMS Impl
> Affects Versions: 2.1.3
> Environment: Ubuntu 8.0.4 AMD64, ActiveMQ 5.1.0 running inside JBoss
> 4.2.2, ActiveMQ-CPP 2.1.3
> Reporter: Aaron Riekenberg
> Assignee: Timothy Bish
> Fix For: 2.2
>
> Attachments: ActiveMQException.cpp.patch
>
>
> Running the "example" example program, I find I get a segmentation fault in
> "example" if I terminate the message broker while its running. This seems
> like quite a serious problem, I can't have all c++ clients core dump if the
> broker goes down. Full stack trace from gdb is at the bottom.
> Did some digging with gdb and found the "size" variable in
> ActiveMQException::buildMessage is 256, meaning our string was longer than
> 128 so we're going through the loop for the second time:
> (gdb) down
> #3 0x00007fd6a575d90f in
> activemq::exceptions::ActiveMQException::buildMessage (
> this=0x610600,
> format=0x7fd6a5898218 "No valid response received for command: %s, check
> broker.",
> vargs=<value optimized out>) at
> activemq/exceptions/ActiveMQException.cpp:75
> 75 int written = vsnprintf(buffer, size, format, vargs);
> (gdb) p size
> $1 = 256
> ActiveMQException::buildMessage does a vsnprintf to try to write vargs into
> buffer, and if buffer isn't big enough it doubles the size and tries another
> vsnprintf. Trouble is it's only legal to do ONE vsnprintf between calls to
> va_start and va_end, so on the second try vargs is garbage. See "man
> vsnprintf":
> The functions vprintf(), vfprintf(), vsprintf(), vsnprintf() are
> equivalent to the
> functions printf(), fprintf(), sprintf(), snprintf(), respectively,
> except that they
> are called with a va_list instead of a variable number of arguments.
> These functions
> do not call the va_end macro. Because they invoke the va_arg macro,
> the value of ap
> is undefined after the call. See stdarg(3).
> One possible solution is to use va_copy or __va_copy to make a copy of vargs
> so we have a fresh copy to traverse on each iteration in buildMessage. I've
> verified the following works on my system (I have __va_copy instead of
> va_copy on Ubunutu 8.0.4):
> void ActiveMQException::buildMessage(const char* format, va_list& vargs)
> {
> // Allocate buffer with a guess of it's size
> int size = 128;
> // Format string
> while( true ){
> // Allocate a buffer of the specified size.
> char* buffer = new char[size];
> va_list vargsCopy;
> __va_copy(vargsCopy, vargs);
> int written = vsnprintf(buffer, size, format, vargsCopy);
> if (written > -1 && written < size-1) {
> // Guessed size was enough. Assign the string.
> message.assign (buffer, written);
> // assign isn't passing ownership, just copying, delete
> // the allocated buffer.
> delete [] buffer;
> va_end(vargsCopy);
> break;
> }
> // Our buffer wasn't big enough - destroy the old buffer,
> // double the size and try again.
> delete [] buffer;
> va_end(vargsCopy);
> size *= 2;
> }
> //activemq::logger::SimpleLogger logger("com.yadda1");
> //logger.log( message );
> }
> Full stack trace of the failure from gdb:
> Core was generated by
> `/home/aaron/activemq/activemq-cpp-2.1.3-src/src/examples/.libs/lt-example
> '.
> Program terminated with signal 11, Segmentation fault.
> [New process 22513]
> [New process 22517]
> [New process 22497]
> #0 0x00007fd6a4b7c060 in strlen () from /lib/libc.so.6
> (gdb) where
> #0 0x00007fd6a4b7c060 in strlen () from /lib/libc.so.6
> #1 0x00007fd6a4b48e1a in vfprintf () from /lib/libc.so.6
> #2 0x00007fd6a4b6c9ea in vsnprintf () from /lib/libc.so.6
> #3 0x00007fd6a575d90f in
> activemq::exceptions::ActiveMQException::buildMessage (
> this=0x610600,
> format=0x7fd6a5898218 "No valid response received for command: %s, check
> broker.",
> vargs=<value optimized out>) at
> activemq/exceptions/ActiveMQException.cpp:75
> #4 0x00007fd6a57709e8 in CommandIOException (this=0x610600,
> file=0x7fd6a58981e0 "activemq/transport/filters/ResponseCorrelator.cpp",
> lineNumber=145,
> msg=0x7fd6a5898218 "No valid response received for command: %s, check
> broker.")
> at ./activemq/transport/CommandIOException.h:67
> #5 0x00007fd6a57c20d8 in
> activemq::transport::filters::ResponseCorrelator::request (
> this=<value optimized out>, command=<value optimized out>)
> at activemq/transport/filters/ResponseCorrelator.cpp:147
> #6 0x00007fd6a5796735 in
> activemq::connector::openwire::OpenWireFormatNegotiator::request (
> this=0x60ef60, command=0x610688)
> at activemq/connector/openwire/OpenWireFormatNegotiator.cpp:102
> #7 0x00007fd6a57991fa in
> activemq::connector::openwire::OpenWireConnector::syncRequest (
> this=<value optimized out>, command=0x7fd6a5898240)
> at activemq/connector/openwire/OpenWireConnector.cpp:1349
> #8 0x00007fd6a5799dd1 in
> activemq::connector::openwire::OpenWireConnector::send (
> this=0x60d5c0, message=<value optimized out>, producerInfo=<value
> optimized out>)
> at activemq/connector/openwire/OpenWireConnector.cpp:838
> #9 0x00007fd6a5735aec in activemq::core::ActiveMQSession::send (this=<value
> optimized out>,
> message=0x610680, producer=0x6103d0) at
> activemq/core/ActiveMQSession.cpp:673
> #10 0x00007fd6a5741b00 in activemq::core::ActiveMQProducer::send
> (this=0x6103d0,
> destination=<value optimized out>, message=0x610680,
> deliveryMode=626508689, priority=4,
> timeToLive=0) at activemq/core/ActiveMQProducer.cpp:192
> #11 0x00007fd6a574161a in activemq::core::ActiveMQProducer::send
> (this=0x6554514d65766974,
> destination=0x7fd6a5898240, message=0x409a2958) at
> activemq/core/ActiveMQProducer.cpp:147
> #12 0x00007fd6a574193b in activemq::core::ActiveMQProducer::send
> (this=0x6103d0,
> message=0x610680) at activemq/core/ActiveMQProducer.cpp:106
> #13 0x0000000000402bbe in HelloWorldProducer::run (this=0x7fffadd50ff0) at
> main.cpp:114
> #14 0x00007fd6a575bda0 in activemq::concurrent::Thread::runCallback (
> param=<value optimized out>) at activemq/concurrent/Thread.cpp:152
> #15 0x00007fd6a48eb3f7 in start_thread () from /lib/libpthread.so.0
> #16 0x00007fd6a4bd8b2d in clone () from /lib/libc.so.6
> #17 0x0000000000000000 in ?? ()
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