Date: Thu, 5 Nov 2020 21:44:55 -0800 From: Patrick Mahan <plmahan@gmail.com> To: Pete Wright <pete@nomadlogic.org> Cc: questions list <freebsd-questions@freebsd.org> Subject: Re: Helping understand cause of SIGSEGV Message-ID: <CAFDHx1K2-RWS4=xYtNUKMV3t_J7OKKPUE56f9JY45Q%2B0nH_TFA@mail.gmail.com> In-Reply-To: <0764e7ef-bd81-a6c5-47c4-7cd539a428f5@nomadlogic.org> References: <c2eab4b0-b10b-9db3-1aa3-1f61689e24e8@nomadlogic.org> <CAFDHx1Jg_9k3oWU8X-WdP2CJX8hnBYgMz%2BvxwOs766JZcM3WRQ@mail.gmail.com> <0764e7ef-bd81-a6c5-47c4-7cd539a428f5@nomadlogic.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, Nov 5, 2020 at 5:01 PM Pete Wright <pete@nomadlogic.org> wrote: > > > On 11/5/20 4:01 PM, Patrick Mahan wrote: > > > >> | thread #1, name = 'fluent-bit', stop reason = signal SIGABRT >> * frame #0: 0x000000004087100a libc.so.7`__sys_thr_kill at thr_kill.S:4 >> frame #1: 0x00000000407e6c84 libc.so.7`__raise(s=6) at raise.c:52:10 >> frame #2: 0x000000004089a5d9 libc.so.7`abort at abort.c:67:8 >> frame #3: 0x000000000034a7a8 >> fluent-bit`flb_signal_handler(signal=11) at fluent-bit.c:418:9 >> frame #4: 0x00000000406d1c20 >> libthr.so.3`handle_signal(actp=0x00007fffdfffc600, sig=11, >> info=0x00007fffdfffc9f0, ucp=0x00007fffdfffc680) at thr_sig.c:303:3 >> frame #5: 0x00000000406d11ef libthr.so.3`thr_sighandler(sig=11, >> info=0x00007fffdfffc9f0, _ucp=0x00007fffdfffc680) at thr_sig.c:246:2 >> frame #6: 0x00007fffffffe193 >> frame #7: 0x000000000036fe0c fluent-bit`tasks_start [inlined] >> output_params_set(th=0x00000000416091c0, data=0x000000004165d980, >> bytes=128, tag="random.0", tag_len=8, i_ins=0x0000000040e58000, >> out_plugin=0x0000000040e2dfc0, out_context=0x00000000416051e0, >> config=0x0000000040e19180) at flb_output.h:429:5 >> > > I would look at what is happening here in output_params_set(). Something > is accessing out of bounds memory. > > > > thanks for your response Patrick i really appreciate it. > > So here is where output_params_set() is defined - with an interesting > comment that i haven't chased down yet: > > 521 /* Workaround for makecontext() */ > 522 output_params_set(th, > 523 buf, > 524 size, > 525 tag, > 526 tag_len, > 527 i_ins, > 528 o_ins->p, > 529 o_ins->context, > 530 config); > 531 return th; > 532 } > 533 > > and the frame from the backtrace is this for reference: > frame #8: 0x000000000036fd14 fluent-bit`tasks_start [inlined] > flb_output_thread(task=0x00000000416410a0, i_ins=0x0000000040e58000, > o_ins=0x0000000040e5b000, config=0x0000000040e19180, > buf=0x000000004165d980, size=128, tag="random.0", tag_len=8) at > flb_output.h:522 > > and then later on line 429 of flb_output.h it does this: > 428 FLB_TLS_SET(flb_libco_params, params); > 429 co_switch(th->callee); > > like i said i'm not really sure how to grok this, but it sounds like one > of the params in output_params_set isn't being set correctly. hopefully > the code snippet makes the error more obvious :) > > Okay, I don't know lldb very well. But according to the GDB to LLDB command map <http://lldb.llvm.org/use/map.html>; it uses the same commands to move between frames. So at startup you want to ensure you are in thread 1 (thread select 1). That should place you in the last frame on the stack (frame #0). You just move up the stack using the command 'up' until you are in frame #7. Once there you need to dump the contents of 'th' using the command 'p *th' or 'frame variable -T *th'. I suspect the value of th->callee is incorrect. The next frame on the stack is - frame #6: 0x00007fffffffe193 This is different from the rest of the stack addresses. So I suspect it is out of bounds. Patrick
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAFDHx1K2-RWS4=xYtNUKMV3t_J7OKKPUE56f9JY45Q%2B0nH_TFA>