Crash in bluetooth tester when executing BAP/BSRC/SCC/BV-21-C qualification test

[sjanc]

Describe the bug

When executing BAP/BSRC/SCC/BV-21-C tester application may crash if PA sync was lost during BIG sync.

==73468==ERROR: AddressSanitizer: SEGV on unknown address 0x00000000 (pc 0xf75dff96 bp 0xf27ff0c8 sp 0xf27ff0a8 T7)
==73468==The signal is caused by a READ memory access.
==73468==Hint: address points to the zero page.
    #0 0xf75dff96 in memcpy ../sysdeps/i386/i686/memcpy.S:71
    #1 0x0804e0f1 in iso_sync_receiver_big_stopped_cb zephyr/zephyr/tests/bluetooth/tester/src/btp_gap.c:2542
    #2 0x080cfef9 in big_disconnect zephyr/zephyr/subsys/bluetooth/host/iso.c:2734
    #3 0x0807d5dc in hci_event zephyr/zephyr/subsys/bluetooth/host/hci_core.c:3174
    #4 0x0807d5dc in rx_work_handler zephyr/zephyr/subsys/bluetooth/host/hci_core.c:4528
    #5 0x080ea118 in work_queue_main zephyr/zephyr/kernel/work.c:737
    #6 0x08065e5c in z_thread_entry zephyr/zephyr/lib/os/thread_entry.c:48
    #7 0x080779fb in posix_arch_thread_entry zephyr/zephyr/arch/posix/core/thread.c:96
    #8 0x080f5a9a in nct_thread_starter zephyr/zephyr/scripts/native_simulator//common/src/nct.c:291
    #9 0xf785b8fd in asan_thread_start(void*) (/lib/libasan.so.8+0x248fd) (BuildId: 05fd1dd2e1b8ee070f2edf186addec05ce469278)

Regression

• This is a regression.

Steps to reproduce

No response

Relevant log output

Impact

Annoyance – Minor irritation; no significant impact on usability or functionality.

Environment

No response

Additional Context

No response

[sjanc]

fixed by #99018