[pkg-lighttpd] Bug#471409: lighttpd: SEGV when daemon spawns child; clone() call segfaults

[Pierre Habouzit]

On Tue, Mar 18, 2008 at 01:38:16AM +0000, Simon Raven wrote:
> Package: lighttpd
> Version: 1.4.19-1
> Severity: normal
> 
> hi,
> 
> i'm filing this from an x86 box, but the bug is in PPC, i don't see this behaviour 
> in x86. i've run the daemon through strace, and right when it spawns off a child with
> clone(), the parent SEGVs, making the pid file for s-s-d, and other issues, go buggery.
> 
> 
> a bit before, and a bit after what i said:
> 
> =====
> 12428 rt_sigaction(SIGTTOU, {SIG_IGN}, {SIG_DFL}, 8) = 0
> 12428 rt_sigaction(SIGTTIN, {SIG_IGN}, {SIG_DFL}, 8) = 0
> 12428 rt_sigaction(SIGTSTP, {SIG_IGN}, {SIG_DFL}, 8) = 0
> 12428 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x4801c3e8) = 12429
> 12428 --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> 12429 rt_sigaction(SIGPIPE, {SIG_IGN},  <unfinished ...>
> 12428 +++ killed by SIGSEGV +++
> 12429 <... rt_sigaction resumed> {SIG_DFL}, 8) = 0
> 12429 getsockname(11, {sa_family=AF_FILE, path=@}, [2]) = 0
> 12429 getpeername(11, {sa_family=AF_FILE, path="/var/run/slapd/ldapi"}, [23]) = 0
> 12429 fcntl64(11, F_GETFD)              = 0x1 (flags FD_CLOEXEC)
> =====
> 
> the bug has existed since a few package versions ago. i've tried backports, same problem.
> as a consequnce of this bug, the package configuration fails.
> 
> thanks
> simon

  Well, strace is not the proper tool to understand segfaults, and a
backtrace would really help.

  Though, you will need to rebuild lighttpd keeping debug symbols, and
run it again with ulimit -c unlimited, and setting your
/proc/sys/kernel/core_pattern to e.g. /tmp/%e.%p.core so that lighttpd
cores go to /tmp/lighttpd.$PID.core.

  Then use gdb to read the backtrace.

  Running lighttpd under valgrind may help.

-- 
·O·  Pierre Habouzit
··O                                                madcoder at debian.org
OOO                                                http://www.madism.org
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