Greetings, and thank you so much for your very detailed and helpful
report!
You may be interested to know as an aside that maxima/gcl uses a very
sophisticated garbage collecting system which intentionally relies on
segfaults to manage read-only memory. This does make such debugging
more difficult, as one has to determine why the system could not recover
from the fault by re-protecting the page read-write.
In this case I think I know the answer -- this should be fixed with the
next upload, 5.31.3-2. Please let me know if problems persist.
Take care,
Robert Jacobs <debbts...@eamp.org> writes:
> Package: maxima
> Version: 5.31.0-4
> Severity: important
>
> Dear Maintainer,
>
> I've had bug #678404 recur on ia32. (Sorry if I should have reopened that one
> instead)
>
> $ gdb /usr/lib/maxima/5.31.0/binary-gcl/maxima
> Program received signal SIGSEGV, Segmentation fault.
> 0x00068179 in ?? ()
> (gdb) bt
> #0 0x00068179 in ?? ()
> #1 0x00069955 in ?? ()
> #2 0x000b4c94 in malloc ()
> #3 0xb7c4fa51 in __GI___strdup (s=0xbffffdb4 "QT_IM_MODULE=xim") at
> strdup.c:42
> #4 0x00021a0e in ?? ()
> #5 0xb7beb8c5 in __libc_start_main (main=0x20bf0, argc=1, ubp_av=0xbffff594,
> init=0x31ccd0, fini=0x31cd40, rtld_fini=0xb7fee0c0 <_dl_fini>,
> stack_end=0xbffff58c) at libc-start.c:260
> #6 0x00021e78 in ?? ()
> (gdb) disas $eip,+20
> Dump of assembler code from 0x68179 to 0x6818d:
> => 0x00068179: mov DWORD PTR [eax+0x4],edi
> 0x0006817c: add esp,0x6c
> 0x0006817f: mov eax,0x1
> 0x00068184: pop ebx
> 0x00068185: pop esi
> 0x00068186: pop edi
> 0x00068187: pop ebp
> 0x00068188: ret
> 0x00068189: fstp st(0)
> 0x0006818b: fld1
> (gdb) info registers
> eax 0x8a8cb0 9079984
> ecx 0x438000 4423680
> edx 0x7 7
> ebx 0x2335 9013
> esp 0xbffff280 0xbffff280
> ebp 0x32d 0x32d
> esi 0x1 1
> edi 0x5dc740 6145856
> eip 0x68179 0x68179
> eflags 0x10246 [ PF ZF IF RF ]
> cs 0x73 115
> ss 0x7b 123
> ds 0x7b 123
> es 0x7b 123
> fs 0x0 0
> gs 0x33 51
> (gdb) x (int *)0x8a8cb4
> 0x8a8cb4: 0x005dc740
> [...]
> cat /proc/[pid]/maps
> [...]
> 00885000-008a9000 r-xp 0086c000 09:00 805313494
> /usr/lib/maxima/5.31.0/binary-gcl/maxima
> 008a9000-008d6000 rwxp 00890000 09:00 805313494
> /usr/lib/maxima/5.31.0/binary-gcl/maxima
> [...]
>
> So it's trying to update a pointer that's (barely) not in a writeable page.
>
> strace:
> [...]
> personality(0xffffffff /* PER_??? */) = 0
> personality(0x8240000 /* PER_??? */) = 0
> personality(0xffffffff /* PER_??? */) = 0x8240000
> mprotect(0x7ae000, 26652672, PROT_READ|PROT_WRITE|PROT_EXEC) = 0
> rt_sigaction(SIGSEGV, {0x25f30, [SEGV], SA_STACK|SA_RESTART|SA_SIGINFO},
> NULL, 8) = 0
> brk(0) = 0x345d000
> brk(0x3679000) = 0x3679000
> --- SIGSEGV (Segmentation fault) @ 0 (0) ---
>
> ltrace:
> [...]
> [pid 16410] memset(0x01389608, '\000', 26112)
> = 0x01389608
> [pid 16410] sbrk(0)
> = 0x02adf000
> [pid 16410] sbrk(0)
> = 0x02adf000
> [pid 16410] sbrk(2211840)
> = 0x02adf000
> [pid 16410] --- SIGSEGV (Segmentation fault) ---
>
>
> I looked into the process of getting debugging symbols but it looks a
> bit daunting.
>
> As far as I know, neither SELinux nor any other thing should be
> messing up permissions; sbrk and brk (obviously) don't look like
> they're randomized, and the personality() call seemed to have returned
> success.
>
> Bisecting using snapshot.debian.org shows this started happening
> between 5.31.0-1 and 5.31.0-3, and only on ia32. (My amd64 machine
> works fine)
>
> Is there anything else I should try?
>
> Thanks-
> - Robert Jacobs
>
>
> -- System Information:
> Debian Release: jessie/sid
> APT prefers unstable
> APT policy: (500, 'unstable'), (500, 'stable')
> Architecture: i386 (i686)
>
> Kernel: Linux 3.10-1-686-pae (SMP w/1 CPU core)
> Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
>
> Versions of packages maxima depends on:
> ii gnuplot-x11 4.6.4-1
> ii libc6 2.17-93
> ii libgmp10 2:5.1.2+dfsg-3
> ii libreadline6 6.2+dfsg-0.1
> ii libx11-6 2:1.6.2-1
>
> Versions of packages maxima recommends:
> ii maxima-share 5.31.0-4
>
> Versions of packages maxima suggests:
> ii maxima-doc 5.31.0-4
> pn maxima-emacs <none>
> pn texmacs <none>
> ii tk8.4 [wish] 8.4.20-1
> ii tk8.5 [wish] 8.5.14-2
> ii xmaxima 5.31.0-4
>
> -- no debconf information
>
>
>
>
--
Camm Maguire c...@maguirefamily.org
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