Hard fault during supl_session after accessing the Flash

[Rafalino]

Hello , 

I'm  using ncs v1.5.0 , SUPL client library v0.7.0 and modem FW mfw_nrf9160_1.2.3.

It seems that if I am accessing the Flash area in my application and afterwards I start SUPL session I get the following HARD FAULT:

[[00:00:15.650,238] <inf> gps_app: Starting SUPL session
[00:00:26.205,932] [1;31m<err> os: Exception occurred in Secure State
[00:00:26.205,932] [1;31m<err> os: ***** HARD FAULT *****
[00:00:26.205,932] [1;31m<err> os: Fault escalation (see below)
[00:00:26.205,963] [1;31m<err> os: ***** BUS FAULT *****
[00:00:26.205,963] [1;31m<err> os: Precise data bus error
[00:00:26.205,963] [1;31m<err> os: BFAR Address: 0x50008158
[00:00:26.205,993] [1;31m<err> os: r0/a1: 0x00000000 r1/a2: 0x200190a4 r2/a3: 0x200190a0
[00:00:26.205,993] [1;31m<err> os: r3/a4: 0xbe0245f9 r12/ip: 0x0005ccbb r14/lr: 0x00034281
[00:00:26.205,993] [1;31m<err> os: xpsr: 0x61000000
[00:00:26.206,024] [1;31m<err> os: s[ 0]: 0x00000000 s[ 1]: 0x00000000 s[ 2]: 0x00000000 s[ 3]: 0x00000000
[00:00:26.206,054] [1;31m<err> os: s[ 4]: 0x00000000 s[ 5]: 0x00000000 s[ 6]: 0x00000000 s[ 7]: 0xffffffff
[00:00:26.206,054] [1;31m<err> os: s[ 8]: 0x00000000 s[ 9]: 0x00000000 s[10]: 0x00000000 s[11]: 0x00000000
[00:00:26.206,054] [1;31m<err> os: s[12]: 0x00000000 s[13]: 0x00000000 s[14]: 0x00000000 s[15]: 0x00000000
[00:00:26.206,085] [1;31m<err> os: fpscr: 0x00000000
[00:00:26.206,085] [1;31m<err> os: Faulting instruction address (r15/pc): 0x000342b6
[00:00:26.206,085] [1;31m<err> os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
[00:00:26.206,115] [1;31m<err> os: Current thread: 0x20016cc0 (unknown)
[00:00:26.742,675] [1;31m<err> fatal_error: Resetting system
*** Booting Zephyr OS build v2.4.99-ncs1 ***

What could be the reason?

[Rafalino]

Update -

I found the root cause for this crash.

At the beginning of my application , I have accessed the flash and wrote a buffer that was allocated with k_malloc.

Later on I released the buffer with free and not k_free and when I started  SUPL session I got the crash.

When I replaced the free with k_free the crash disappeared.