Tested Asan test as follows with command "runqemu nographic"
(with IMAGE_INSTALL:append = " libasan  libasan-dev"):

root@qemuriscv64:~# gcc -g -fsanitize=address -o asan_test asan_test.c

root@qemuriscv64:~# ./asan_test 

Running AddressSanitizer test...

=================================================================

==262==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x003f9380002a at pc 0x002add509b88 bp 0x003ff6510ec0 sp 0x003ff6510e90

WRITE of size 1 at 0x003f9380002a thread T0

    #0 0x2add509b86 in cause_buffer_overflow /home/root/a.c:9

    #1 0x2add509ca2 in main /home/root/a.c:16

    #2 0x3f95a917b4  (/lib/libc.so.6+0x277b4) (BuildId: 89440b2a8f8e9f78366a816e4685a39d6a4de4c5)

    #3 0x3f95a9185c in __libc_start_main (/lib/libc.so.6+0x2785c) (BuildId: 89440b2a8f8e9f78366a816e4685a39d6a4de4c5)

    #4 0x2add509a1e in _start ../sysdeps/riscv/start.S:67

 

Address 0x003f9380002a is located in stack of thread T0 at offset 42 in frame

    #0 0x2add509ac4 in cause_buffer_overflow /home/root/a.c:5

 

  This frame has 1 object(s):

    [32, 42) 'buffer' (line 6) <== Memory access at offset 42 overflows this variable

HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork

      (longjmp and C++ exceptions *are* supported)

SUMMARY: AddressSanitizer: stack-buffer-overflow /home/root/a.c:9 in cause_buffer_overflow

Shadow bytes around the buggy address:

  0x003f937ffd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f937ffe00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f937ffe80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f937fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f937fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

=>0x003f93800000: f1 f1 f1 f1 00[02]f3 f3 00 00 00 00 00 00 00 00

  0x003f93800080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f93800100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f93800180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f93800200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x003f93800280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

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