I am trying to debug my c++ programming assignment application using gdb on an Ubuntu server, because it produces segmentation fault.
But the file produces ?? symbols that are unreadable to me when I try bt it gives me.
(gdb) bt
#0 0x00007f141956d277 in ?? ()
#1 0x00007ffc1a866bd0 in ?? ()
#2 0x000055e1f101d5e0 in ?? ()
#3 0x00007ffc1a866db0 in ?? ()
#4 0x000055e1f1433e70 in ?? ()
#5 0x00007ffc1a866bd0 in ?? ()
#6 0x000055e1f10224a9 in ?? ()
#7 0x000055e1f14341f8 in ?? ()
#8 0x00000001f14344d0 in ?? ()
#9 0x0000000000000000 in ?? ()
I was following this link, and it told me to load these symbols
symbol-file /path/to/my/binary
sharedlibrary
The sharedlibrary was found, but the symbol-file path is not there. So,it did change bt command output somehow
(gdb) bt
#0 tcache_get (tc_idx=0) at malloc.c:2943
#1 _GI__libc_malloc (bytes=19) at malloc.c:3050
#2 0x000055e1f10224a9 in ?? ()
#3 0x000055e1f14341f8 in ?? ()
#4 0x00000001f14344d0 in ?? ()
#5 0x0000000000000000 in ?? ()
I still don't understand the bug.
Now, I don't know it's a problem from the GDB for not having this symbol-file or its a compilation problem which I don't know how or that's enough for me to debug, but I was following Debugging a Segmentation Fault and it was much clearer to troubleshoot.
When I search for similar cases, all of them were answered only for their case, not a general solution how to deal with these kinds of error. I also thought of installing or locating that symbol-file but I didn't understand how.
If someone could help me, I need to understand what is my problem and how should I fix it.
Note: core dump is produced in the /tmp not in current application directory
I was following this link, and it told me to load these symbols
Don't follow this link (it's unnecessarily complicated for your use case).
Instead, do this:
gdb /path/to/my/binary
(gdb) run
... GDB will stop when your program encounters SIGSEGV
(gdb) bt # should produce meaningful output now.
Related
GDB 7.7 shows more number of backtraces (90) for my core file. It is problem with GDB or core file or stack corruption issue?
(gdb) bt
Python Exception exceptions.ImportError No module named traceback:
#0 0x00007f422fd04c37 in ?? () from /users/jegan/lib/x86_64-linux-gnu/libc.so.6
#1 0x0000000000002929 in ?? ()
#2 0x7328203c20746e63 in ?? ()
.......................
......................
#88 0x544143494649544e in ?? ()
#89 0x29295d305b4e4f49 in ?? ()
#90 0x0000000000000000 in ?? ()
(gdb)
GDB 7.7 shows more number of backtraces (90) for my core file.
There are a few likely causes for this:
You didn't invoke GDB correctly, or
You are analysing a core dump on a different host from the one it was produced on (or the same host has had its system libraries updated).
Answer for #1.
Answer for #2.
I'm using the Point Cloud Library with cmake for compilation, and I've got it building in debug mode, but my program doesn't seg fault or abort in the way I'd expect it to.
Specifically, I get messages like this:
(gdb) run bunny
Starting program: debug/our_cvfh bunny
libc++abi.dylib: terminating
[New Thread 0x170b of process 80178]
Program received signal SIGABRT, Aborted.
0x00007fff88c6f866 in ?? ()
(gdb) bt
#0 0x00007fff88c6f866 in ?? ()
#1 0x00007fff8bb5235c in ?? ()
#2 0x0000000000000000 in ?? ()
(gdb) break rec/registered_views_source.h:305
Cannot access memory at address 0x961d60
In this case, I know where the error is, but I'd like to be able to backtrace it and see what called the function in this case.
Is PCL creating another thread, and that's why I can't backtrace? I'm not doing any visualizations right now, so I can't figure out why it'd be using threading.
I've also tried running the program in the debug directory instead of from my source root directory. Here's another example of it not working:
$ gdb our_cvfh
GNU gdb (GDB) 7.7
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin13.1.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from our_cvfh...done.
run (gdb) run
Starting program: /Users/jwoods/Projects/lidargl/fpfh/debug/our_cvfh
[New Thread 0x170b of process 33571]
Program received signal SIGSEGV, Segmentation fault.
0x000000010016cdec in ?? ()
(gdb) bt
#0 0x000000010016cdec in ?? ()
#1 0x00007fff5fbfbd08 in ?? ()
#2 0x00007fff5fbfbcc0 in ?? ()
#3 0x00007fff5fbfbcc8 in ?? ()
#4 0x00007fff5fbfbcc8 in ?? ()
#5 0x00007fff5fbfbcc8 in ?? ()
#6 0xffffffffffffffff in ?? ()
#7 0x00007fff5fbfbcc8 in ?? ()
#8 0x00007fff5fbfbcc8 in ?? ()
#9 0x00007fff5fbfbcc0 in ?? ()
#10 0x00007fff5fbfbcc0 in ?? ()
#11 0x00007fff5fbfbcc8 in ?? ()
#12 0x00007fff5fbfbcc8 in ?? ()
#13 0x00007fff5fbfbcc8 in ?? ()
#14 0x00007fff5fbff4a8 in ?? ()
#15 0x00007fff5fbff4d8 in ?? ()
#16 0x00007fff5fbff420 in ?? ()
#17 0x00007fff5fbff4d8 in ?? ()
#18 0x0000000000000000 in ?? ()
(gdb)
gdb works fine when I'm not using CMake, so my guess is it has something to do with CMake. This doesn't seem to present a problem for anyone else, which tells me it may also have to do with the fact that I'm using CMake with Mac OS X.
How do I get my normal GDB behavior?
Update
I can run dsymutil my_output_binary in order to generate the debugging symbols (following make). This is a workaround. I'd like it to be done automatically, and amn't sure why it's not. The dsymutil strategy works for most segfaults, but doesn't work for some cases of SIGABRT. Here is the output:
Calling compute <--- normal std::cerr output of my program, single-threaded
Assertion failed: (index >= 0 && index < size()), function operator[], file /usr/local/Cellar/eigen/3.2.1/include/eigen3/Eigen/src/Core/DenseCoeffsBase.h, line 378.
[New Thread 0x170b of process 64108]
Program received signal SIGABRT, Aborted.
0x00007fff84999866 in ?? ()
(gdb) bt
#0 0x00007fff84999866 in ?? ()
#1 0x00007fff862c335c in ?? ()
#2 0x0000000000000000 in ?? ()
(gdb) info threads
Id Target Id Frame
2 Thread 0x170b of process 64108 0x00007fff8499a662 in ?? ()
* 1 Thread 0x1503 of process 64108 0x00007fff84999866 in ?? ()
(gdb)
Note that my program is not itself multi-threaded, but it appears to be making use of a library which is creating threads — or at least that's what I gather from the gdb output.
I've tried disabling threading with Eigen, which is used by PCL.
Interestingly, lldb is able to generate the backtraces, but I'm curious as to why GDB can't.
Other than simply using LLDB in lieu of GDB, I haven't figured out how to debug threads.
However, I have figured out how to automatically produce debugging symbols! Hooray.
You need three files:
UseCompVer.cmake
AddOptions.cmake
UseDebugSymbols.cmake
Put these in your project's cmake/Modules/ directory.
In CMakeLists.txt, you'll need the following lines after your project declaration:
set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/Modules/")
if (APPLE) # this if statement is optional, but you definitely need the include()
include(UseDebugSymbols)
endif (APPLE)
That will look in the appropriate location.
I should note that I made another change to my project simultaneously, which may also be useful to you. In my add_executable line, right after the name of the target, I added MACOSX_BUNDLE. This flag will cause it to be compiled as a .app instead of a regular binary. Here's an example from my project:
add_executable(pose MACOSX_BUNDLE pose.cpp rec/global_nn_recognizer_cvfh.cpp rec/global_nn_recognizer_cvfh.hpp rec/render_views_tesselated_sphere.cpp)
C++ application gets crashed with the core file showing error
warning: no loadable sections found in added symbol-file system-supplied DSO at 0x7fff79e54000
Core was generated by `./server'.
Program terminated with signal 6, Aborted.
#0 0x0000003b67230265 in raise () from /lib64/libc.so.6
(gdb) bt
#0 0x0000003b67230265 in raise () from /lib64/libc.so.6
#1 0x0000003b67231d10 in abort () from /lib64/libc.so.6
#2 0x0000003b6726a9bb in __libc_message () from /lib64/libc.so.6
#3 0x0000003b6727247f in _int_free () from /lib64/libc.so.6
#4 0x0000003b672728db in free () from /lib64/libc.so.6
#5 0x00000000004060df in operator delete (p=0x20030190) at ../lib/m_string.cpp:43
#6 0x0000000000403892 in TStr::~TStr (this=0x2102c980, __in_chrg=<value optimized out>) at ../lib/m_string.cpp:175 –
could able to understand about this issue. Here is the link that i have verified https://bugzilla.redhat.com/show_bug.cgi?id=959013
shows that the size of vdso file is not enough. which is in path /proc/self/maps.
please let me know what kind of issue is this and please suggest a fix for this.
what kind of issue is this
Any crash inside malloc or free is a sure sign of previous heap corruption.
Use Valgrind or AddressSanitizer (incorporated into GCC-4.8 as well) to find the root cause.
Ignore vdso -- as Tom Tromey said, it has nothing to do with the problem.
I have a program that when I run from terminal (wihtout GDB) prints some outputs. Assume the output looks like
welcome to CMP simulator
initializing
finish initialization
now run
goodbye
Now, when I want to use GDB, the program gives a PID and I use that to attach to GDB. Assume the output of the program now looks like
welcome to CMP simulator
gdb - 5932 (Run this command on another terminal and type "continue" at GDB prompt)
While the program waits for SIGCONT, I run gdb - 5932 on anther terminal. As I type "continue", GDB reports a crash like this:
Loaded symbols for /home/mahmood/results/temp/libCMP_iface_gcc.so
0x00007fd3a499fb7b in raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:42
42 ../nptl/sysdeps/unix/sysv/linux/pt-raise.c: No such file or directory.
(gdb) c
Continuing.
Program received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7fd3a343f700 (LWP 21014)]
0x00007fd3a408e303 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>)
at ../sysdeps/unix/sysv/linux/poll.c:87
87 ../sysdeps/unix/sysv/linux/poll.c: No such file or directory.
(gdb) bt
#0 0x00007fd3a408e303 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>)
at ../sysdeps/unix/sysv/linux/poll.c:87
#1 0x00007fd3a4c0fc4c in ?? () from /home/mahmood/simics-3.0.31/amd64-linux/bin/libsimics-common.so
#2 0x00007fd3a4997e9a in start_thread (arg=0x7fd3a343f700) at pthread_create.c:308
#3 0x00007fd3a4099cbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#4 0x0000000000000000 in ?? ()
(gdb)
At this point, the program still is waiting for SIGCONT.
What does the back trace means?
As you can see without GDB, the program prints more line on the output. However GDB shows a crash. My guess is that there is a problem with creating thread.
Any feedback is appreciated.
UPDATE:
If I ran "continue" again, I see the same output on GDB
(gdb) c
Continuing.
Program received signal SIGSTOP, Stopped (signal).
0x00007f09b653c303 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout= <optimized out>)
at ../sysdeps/unix/sysv/linux/poll.c:87
87 in ../sysdeps/unix/sysv/linux/poll.c
(gdb) bt
#0 0x00007f09b653c303 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>)
at ../sysdeps/unix/sysv/linux/poll.c:87
#1 0x00007f09b70bdc4c in ?? () from /home/mahmood/simics-3.0.31/amd64-linux/bin/libsimics-common.so
#2 0x00007f09b6e45e9a in start_thread (arg=0x7f09b58ed700) at pthread_create.c:308
#3 0x00007f09b6547cbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#4 0x0000000000000000 in ?? ()
(gdb)
The system is ubuntu 12.04 amd64
GDB isn't showing a crash, a SIGSTOP just means the program wasa stopped and you just have to continue it using gdb command 'continue' or just asking to GDB to send the signal using 'sig SIGCONT'
I hope I help you.
pt-raise.c: No such file or directory
This error can be fixed by rebuilding gdb from sources
Here is the problem which I'm trying to address:
We've got a core dump while processing data. The result of backtracing is:
#0 0x00a99402 in __kernel_vsyscall ()
#1 0x00306df0 in raise () from /lib/libc.so.6
#2 0x00308701 in abort () from /lib/libc.so.6
#3 0x001c4530 in _gnu_cxx::_verbose_terminate_handler() () from /usr/lib/libstdc++.so.6
#4 0x001c1f35 in ?? () from /usr/lib/libstdc++.so.6
#5 0x001c12ca in ?? () from /usr/lib/libstdc++.so.6
#6 0x001c1d99 in __gxx_personality_v0 () from /usr/lib/libstdc++.so.6
#7 0x00d1c7e6 in ?? () from /lib/libgcc_s.so.1
#8 0x00d1cb62 in _Unwind_Resume () from /lib/libgcc_s.so.1
........
I've looked through the code base of our application and it is not clear that the problem is due to uncaught exception or whatever (but i know it somehow connected with exceptions because of _Unwind_Resume call is there). So I'm trying to write simple program which also fails with core dump and its gdb backtracing contains the lines above.
os: CentOS, compiler: gnu gcc 4.1.2, language: c/c++
Any suggestions about the problem/code would be much appreciated