I'm not sure yet what's the exact issue, but I don't see the segfault after disabling the alloc plugin (`dmtcp_launch --disable-alloc-plugin`). Could you try and see if it helps you too?
The error has some thing to do with calls to dlerror() from libltdl when doing a symbol lookup. The function dlerror, in turn, calls malloc/realloc, which lands up in the wrappers defined in the alloc plugin. On Wed, May 25, 2016 at 06:43:36AM -0400, Rohan Garg wrote: > Hi Kyle, > > I investigated this a little further. Interestingly, I'm not able > to reproduce this locally with ImageMagick-6.9.3, and DMTCP-2.5-rc2. > This is on OpenSUSE-Tumbleweed, with gcc-5.3.1 and glibc-2.23. > Here's what I did: > > $ dmtcp_launch convert ./test1.jpg ./test2.png > > To verify that it's calling in to ltdl, I ran it under gdb and put a > breakpoint on `lt_dlsym`. Indeed, it does call in to libltdl, but I > didn't get a segfault. > > However, I can confirm that I can reproduce the bug with your simple > ltdl test program. :-) I'll continue to look at it. Also, if you don't > mind, I'd like to open a new issue on Github to keep a track of this. > > Thanks, > Rohan > > On Tue, May 24, 2016 at 12:22:40AM -0400, Kyle Harrigan wrote: > > Yes, I think I've confirmed it is libltdl. Trivial test case is here: > > https://github.com/kwharrigan/dl_vs_ltdl. > > > > dl and ltdl test both work fine outside of DMTCP. Under dmtcp_launch, dl > > works but ltdl fails w/ basically the same stack trace I got in the other > > case. Also note that launching ImageMagick "convert" directly under > > dmtcp_launch also fails. > > > > > > > > > > > > > > > > > > > > > > > > > > > > On Sun, May 22, 2016 at 6:11 PM, Jiajun Cao <jia...@ccs.neu.edu> wrote: > > > > > Hi Kyle, > > > > > > To confirm it's libltdl that causes the problem, you can write a simple > > > program that calls lt_dlsym (lt_dlopen if necessary), and returns. Run the > > > program under DMTCP to see if it crashes. > > > DMTCP doesn't have special handling for libltdl. It deals with libdl > > > instead. I wonder if that is the issue. You can replace lt_dlsym with > > > dlsym > > > to verify the theory. Libdl should work fine under DMTCP. > > > > > > Best, > > > Jiajun > > > > > > On Sat, May 21, 2016 at 1:04 PM, Kyle Harrigan <kwharri...@gmail.com> > > > wrote: > > > > > >> Oh, and in case it matters ... ImageMagick-6.7.2, CentOS 6.7, > > >> libtool-ltdl-2.2.6-15.5.el6.x86_64, Kernel 2.6.32-573.26.1.el6.x86_64 #1 > > >> SMP Wed May 4 00:57:44 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux > > >> > > >> > > >> On Sat, May 21, 2016 at 1:00 PM, Kyle Harrigan <kwharri...@gmail.com> > > >> wrote: > > >> > > >>> Consider the following code > > >>> {{{ > > >>> FILE *fh; > > >>> FILE *p; > > >>> char *buf; > > >>> size_t result; > > >>> long fsize; > > >>> > > >>> fh = fopen("demo.pgm", "rb"); > > >>> > > >>> // allocate buffer to hold file > > >>> fseek(fh, 0, SEEK_END); > > >>> fsize = ftell(fh); > > >>> rewind(fh); > > >>> buf = (char*) malloc(sizeof(char)*fsize); > > >>> > > >>> // read from the source file > > >>> result = fread(buf, 1, fsize, fh); > > >>> printf("result: %d\n", result); > > >>> fclose(fh); > > >>> > > >>> // pipe to convert and write to png > > >>> p = popen("convert pgm:- out.png", "w"); > > >>> //p = popen("cat - > out.pgm", "w"); > > >>> fwrite(buf, 1, fsize, p); > > >>> pclose(p); > > >>> free(buf); > > >>> }}} > > >>> > > >>> Run as: > > >>> $ dmtcp_launch ./test_convert > > >>> > > >>> It basically loads a file into memory, then pipes it into the convert > > >>> function via popen and stdin. > > >>> > > >>> This segment runs fine outside of DMTCP, but segfaults inside. > > >>> > > >>> An examination of the core dump is interesting. > > >>> > > >>> $ gdb /usr/bin/convert core.31830 > > >>> > > >>> (gdb) bt > > >>> #0 0x00000034ec00f6ab in raise (sig=11) at > > >>> ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:42 > > >>> #1 0x0000003a37914e3f in MagickSignalHandler (signal_number=11) at > > >>> magick/magick.c:1168 > > >>> #2 <signal handler called> > > >>> #3 0x00000034ec40142e in __dlerror () at dlerror.c:95 > > >>> #4 0x00000034fde06685 in ?? () from /usr/lib64/libltdl.so.7 > > >>> #5 0x00000034fde03986 in lt_dlsym () from /usr/lib64/libltdl.so.7 > > >>> #6 0x0000003a37919965 in OpenModule (module=<value optimized out>, > > >>> exception=0x224d590) > > >>> at magick/module.c:1293 > > >>> #7 0x0000003a379151f3 in GetMagickInfo (name=0x7ffcd0f386a0 "PGM", > > >>> exception=0x224d590) > > >>> at magick/magick.c:442 > > >>> > > >>> So, it is attempting to dynamically load the module to process the PGM > > >>> file. Bad things appear to start near lt_dlsym, where a __dlerror is > > >>> thrown. > > >>> > > >>> I'm happy to do some further testing, and the above example should allow > > >>> you to test on your own as well. If PGM is a weird input for you, I've > > >>> reproduced the error using PNG inputs, so it does not appear specific to > > >>> that library, but that the dynamic loader is pretty consistently > > >>> failing. > > >>> > > >>> > > >>> -- > > >>> -Kyle > > >>> > > >> > > >> > > >> > > >> -- > > >> -Kyle > > >> > > >> > > >> ------------------------------------------------------------------------------ > > >> Mobile security can be enabling, not merely restricting. Employees who > > >> bring their own devices (BYOD) to work are irked by the imposition of MDM > > >> restrictions. Mobile Device Manager Plus allows you to control only the > > >> apps on BYO-devices by containerizing them, leaving personal data > > >> untouched! > > >> https://ad.doubleclick.net/ddm/clk/304595813;131938128;j > > >> _______________________________________________ > > >> Dmtcp-forum mailing list > > >> Dmtcp-forum@lists.sourceforge.net > > >> https://lists.sourceforge.net/lists/listinfo/dmtcp-forum > > >> > > >> > > > > > > > > > -- > > -Kyle > > > ------------------------------------------------------------------------------ > > Mobile security can be enabling, not merely restricting. Employees who > > bring their own devices (BYOD) to work are irked by the imposition of MDM > > restrictions. Mobile Device Manager Plus allows you to control only the > > apps on BYO-devices by containerizing them, leaving personal data untouched! > > https://ad.doubleclick.net/ddm/clk/304595813;131938128;j > > > _______________________________________________ > > Dmtcp-forum mailing list > > Dmtcp-forum@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/dmtcp-forum > > > ------------------------------------------------------------------------------ > Mobile security can be enabling, not merely restricting. Employees who > bring their own devices (BYOD) to work are irked by the imposition of MDM > restrictions. Mobile Device Manager Plus allows you to control only the > apps on BYO-devices by containerizing them, leaving personal data untouched! > https://ad.doubleclick.net/ddm/clk/304595813;131938128;j > _______________________________________________ > Dmtcp-forum mailing list > Dmtcp-forum@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/dmtcp-forum ------------------------------------------------------------------------------ Mobile security can be enabling, not merely restricting. Employees who bring their own devices (BYOD) to work are irked by the imposition of MDM restrictions. Mobile Device Manager Plus allows you to control only the apps on BYO-devices by containerizing them, leaving personal data untouched! https://ad.doubleclick.net/ddm/clk/304595813;131938128;j _______________________________________________ Dmtcp-forum mailing list Dmtcp-forum@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dmtcp-forum
