OsmocomBB

(gdb) frame 8
#8  0x00007ffff6b922c0 in osmo_wqueue_bfd_cb (fd=0x6110000006f8, what=3)
    at /home/pespin/dev/sysmocom/git/libosmocore/src/core/write_queue.c:61
61                        fd->when &= ~OSMO_FD_WRITE;
(gdb) print queue->write_cb
$1 = (int (*)(struct osmo_fd *,
    struct msgb *)) 0x55555560f717 <l1ctl_client_write_cb>
(gdb) print queue->read_cb
$2 = (int (*)(struct osmo_fd *)) 0x555555610b4b <l1ctl_client_read_cb>

I'm building with --enable-sanitize and following options:

        export CPPFLAGS="-ggdb3 -Og -fno-omit-frame-pointer" 
        export CFLAGS="-ggdb3 -Og -fno-omit-frame-pointer" 
        export CXXFLAGS="-ggdb3 -Og -fno-omit-frame-pointer" 

I added the -d flags you requested:

20230130180939417 DL1D NOTICE trxcon(0)[0x612000019ba0]: L1CTL connection error: read() failed (rc=-1): Connection reset by peer (l1ctl_server.c:55)
20230130180939417 DL1C NOTICE trxcon(0)[0x612000019ba0]: Closing L1CTL connection (l1ctl_server.c:206)
20230130180939417 DSCH NOTICE trxcon(0)[0x612000019ba0]: Shutdown scheduler (sched_trx.c:206)
20230130180939417 DSCH NOTICE trxcon(0)[0x612000019ba0]: Delete TDMA timeslot #0 (sched_trx.c:264)
20230130180939417 DTRXC NOTICE trx_interface(0)[0x612000019ea0]{ACTIVE}: Shutdown transceiver interface (trx_if.c:830)
=================================================================
==57254==ERROR: AddressSanitizer: heap-use-after-free on address 0x6110000005cc at pc 0x7ffff6baa463 bp 0x7fffffffde30 sp 0x7fffffffde20
READ of size 4 at 0x6110000005cc thread T0
    #0 0x7ffff6baa462 in osmo_wqueue_bfd_cb /home/pespin/dev/sysmocom/git/libosmocore/src/core/write_queue.c:61
    #1 0x7ffff6b74fc2 in poll_disp_fds /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:361
    #2 0x7ffff6b750c2 in _osmo_select_main /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:399
    #3 0x7ffff6b7516b in osmo_select_main /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:438
    #4 0x555555614025 in main /home/pespin/dev/sysmocom/git/osmocom-bb/src/host/trxcon/src/trxcon_main.c:389
    #5 0x7ffff703c28f  (/usr/lib/libc.so.6+0x2328f)
    #6 0x7ffff703c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
    #7 0x55555560d9a4 in _start (/home/pespin/dev/sysmocom/build/new/out/bin/trxcon+0xb99a4)

0x6110000005cc is located 140 bytes inside of 240-byte region [0x611000000540,0x611000000630)
freed by thread T0 here:
    #0 0x7ffff78be672 in __interceptor_free /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:52
    #1 0x7ffff7ed8002  (/usr/lib/libtalloc.so.2+0x4002)
    #2 0x555555610cb8 in l1ctl_client_read_cb /home/pespin/dev/sysmocom/git/osmocom-bb/src/host/trxcon/src/l1ctl_server.c:63
    #3 0x7ffff6baa01d in osmo_wqueue_bfd_cb /home/pespin/dev/sysmocom/git/libosmocore/src/core/write_queue.c:47
    #4 0x7ffff6b74fc2 in poll_disp_fds /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:361
    #5 0x7ffff6b750c2 in _osmo_select_main /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:399
    #6 0x7ffff6b7516b in osmo_select_main /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:438
    #7 0x555555614025 in main /home/pespin/dev/sysmocom/git/osmocom-bb/src/host/trxcon/src/trxcon_main.c:389
    #8 0x7ffff703c28f  (/usr/lib/libc.so.6+0x2328f)

previously allocated by thread T0 here:
    #0 0x7ffff78bfa89 in __interceptor_malloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:69
    #1 0x7ffff7ed8b5f  (/usr/lib/libtalloc.so.2+0x4b5f)

SUMMARY: AddressSanitizer: heap-use-after-free /home/pespin/dev/sysmocom/git/libosmocore/src/core/write_queue.c:61 in osmo_wqueue_bfd_cb
Shadow bytes around the buggy address:
  0x0c227fff8060: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c227fff8070: fd fd fd fd fd fd fa fa fa fa fa fa fa fa fa fa
  0x0c227fff8080: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c227fff8090: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fa fa
  0x0c227fff80a0: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
=>0x0c227fff80b0: fd fd fd fd fd fd fd fd fd[fd]fd fd fd fd fd fd
  0x0c227fff80c0: fd fd fd fd fd fd fa fa fa fa fa fa fa fa fa fa
  0x0c227fff80d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff80e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff80f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff8100: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==57254==ABORTING

Program received signal SIGABRT, Aborted.
0x00007ffff70a164c in ?? () from /usr/lib/libc.so.6
(gdb) bt
#0  0x00007ffff70a164c in ?? () from /usr/lib/libc.so.6
#1  0x00007ffff7051938 in raise () from /usr/lib/libc.so.6
#2  0x00007ffff703b53d in abort () from /usr/lib/libc.so.6
#3  0x00007ffff78dfce4 in __sanitizer::Abort ()
    at /usr/src/debug/gcc/gcc/libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp:143
#4  0x00007ffff78ed1c2 in __sanitizer::Die ()
    at /usr/src/debug/gcc/gcc/libsanitizer/sanitizer_common/sanitizer_termination.cpp:58
#5  0x00007ffff78c9c20 in __asan::ScopedInErrorReport::~ScopedInErrorReport (
    this=0x7fffffffd1b6, __in_chrg=<optimized out>)
    at /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_report.cpp:190
#6  0x00007ffff78c910c in __asan::ReportGenericError (pc=140737332814947,
    bp=bp@entry=140737488346672, sp=sp@entry=140737488346656,
    addr=106721347372492, is_write=is_write@entry=false,
    access_size=access_size@entry=4, exp=0, fatal=true)
    at /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_report.cpp:479
#7  0x00007ffff78ca38c in __asan::__asan_report_load4 (addr=<optimized out>)
    at /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_rtl.cpp:122
#8  0x00007ffff6baa463 in osmo_wqueue_bfd_cb (fd=0x6110000005b8, what=3)
    at /home/pespin/dev/sysmocom/git/libosmocore/src/core/write_queue.c:61
#9  0x00007ffff6b74fc3 in poll_disp_fds (n_fd=n_fd@entry=4)
    at /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:361
--Type <RET> for more, q to quit, c to continue without paging--
#10 0x00007ffff6b750c3 in _osmo_select_main (polling=polling@entry=0)
    at /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:399
#11 0x00007ffff6b7516c in osmo_select_main (polling=polling@entry=0)
    at /home/pespin/dev/sysmocom/git/libosmocore/src/core/select.c:438
#12 0x0000555555614026 in main (argc=<optimized out>, argv=<optimized out>)
    at /home/pespin/dev/sysmocom/git/osmocom-bb/src/host/trxcon/src/trxcon_main.c:389
(gdb) frame 8
#8  0x00007ffff6baa463 in osmo_wqueue_bfd_cb (fd=0x6110000005b8, what=3)
    at /home/pespin/dev/sysmocom/git/libosmocore/src/core/write_queue.c:61
61                        fd->when &= ~OSMO_FD_WRITE;
(gdb) print queue->write_cb
$1 = (int (*)(struct osmo_fd *,
    struct msgb *)) 0x55555560f717 <l1ctl_client_write_cb>