Hello,
I checked the backtrace of a crashed dhcpd running on 4.4.1-2.1ubuntu5.
(gdb) info threads
Id Target Id Frame
* 1 Thread 0x7fb4ddecb700 (LWP 3170) __GI_raise (sig=sig@entry=6) at
../sysdeps/unix/sysv/linux/raise.c:50
2 Thread 0x7fb4dd6ca700 (LWP 3171) __lll_lock_wait
(futex=futex@entry=0x7fb4de6d2028, private=0) at lowlevellock.c:52
3 Thread 0x7fb4de6cc700 (LWP 3169) futex_wake (private=<optimized out>,
processes_to_wake=1, futex_word=<optimized out>) at
../sysdeps/nptl/futex-internal.h:364
4 Thread 0x7fb4de74f740 (LWP 3148) futex_wait_cancelable
(private=<optimized out>, expected=0, futex_word=0x7fb4de6cd0d0) at
../sysdeps/nptl/futex-internal.h:183
(gdb) frame 2
#2 0x00007fb4dec85985 in isc_assertion_failed (file=file@entry=0x7fb4decd8878
"../../../../lib/isc/unix/socket.c", line=line@entry=3361,
type=type@entry=isc_assertiontype_insist,
cond=cond@entry=0x7fb4decda033 "!sock->pending_send") at
../../../lib/isc/assertions.c:52
(gdb) bt
#1 0x00007fb4deaa7859 in __GI_abort () at abort.c:79
#2 0x00007fb4dec85985 in isc_assertion_failed (file=file@entry=0x7fb4decd8878
"../../../../lib/isc/unix/socket.c", line=line@entry=3361,
type=type@entry=isc_assertiontype_insist,
cond=cond@entry=0x7fb4decda033 "!sock->pending_send") at
../../../lib/isc/assertions.c:52
#3 0x00007fb4decc17e1 in dispatch_send (sock=0x7fb4de6d4990) at
../../../../lib/isc/unix/socket.c:4041
#4 process_fd (writeable=<optimized out>, readable=<optimized out>, fd=11,
manager=0x7fb4de6d0010) at ../../../../lib/isc/unix/socket.c:4054
#5 process_fds (writefds=<optimized out>, readfds=0x7fb4de6d1090, maxfd=13,
manager=0x7fb4de6d0010) at ../../../../lib/isc/unix/socket.c:4211
#6 watcher (uap=0x7fb4de6d0010) at ../../../../lib/isc/unix/socket.c:4397
#7 0x00007fb4dea68609 in start_thread (arg=<optimized out>) at
pthread_create.c:477
#8 0x00007fb4deba4103 in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:95
(gdb) frame 3
#3 0x00007fb4decc17e1 in dispatch_send (sock=0x7fb4de6d4990) at
../../../../lib/isc/unix/socket.c:4041
4041 in ../../../../lib/isc/unix/socket.c
(gdb) p sock->pending_send
$2 = 1
The code is crashing on this assertion:
https://gitlab.isc.org/isc-projects/bind9/-/blob/v9_11_3/lib/isc/unix/socket.c#L3364
This was already reported and marked as fixed in debian (?) via [0]
""Now if a wakeup event occurres the socket would be dispatched for
processing regardless which kind of event (timer?) triggered the wakeup.
At least I did not find any sanity checks in process_fds() except
SOCK_DEAD(sock).
This leads to the following situation: The sock is not dead yet but it
is still pending when it is dispatched again.
I would now check sock->pending_send before calling dispatch_send().This
would at least prevent the assertion failure - well knowing that the
situation described above ( not dead but still pending and alerting ) is
not a very pleasant one - until someone comes up with a better solution.
"""
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=430065#20
** Follow up questions:
0) The reproducer doesn't seems consistent and seems to be related to a race
condition associated with a internal timer/futex.
1) Can anyone confirm that a pristine upstream 4.4.1 doesn't reproduces the
issue?
** Bug watch added: Debian Bug tracker #430065
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=430065
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https://bugs.launchpad.net/bugs/1888926
Title:
tls.tlscfgcmd not recognized; rebuild rsyslog against librelp 1.5.0
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