Re: [Bug 1913669] [NEW] FPE in npcm7xx_adc_convert

[Philippe Mathieu-Daudé]

Cc'ing supporters:

$ ./scripts/get_maintainer.pl -f hw/arm/npcm7xx.c
Havard Skinnemoen <hskinnemoen@google.com> (supporter:Nuvoton NPCM7xx)
Tyrone Ting <kfting@nuvoton.com> (supporter:Nuvoton NPCM7xx)

On 1/29/21 3:36 AM, Alexander Bulekov wrote:
> Public bug reported:
> 
> Reproducer:
> cat << EOF | ./qemu-system-aarch64 -M npcm750-evb \
> -accel qtest -qtest stdio
> write 0xf000c000 0x4 0x02400200
> clock_step
> EOF
> 
> Trace:
> ../hw/adc/npcm7xx_adc.c:60:51: runtime error: division by zero
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior 
> ../hw/adc/npcm7xx_adc.c:60:51 in
> AddressSanitizer:DEADLYSIGNAL
> =================================================================
> ==717962==ERROR: AddressSanitizer: FPE on unknown address 0x55901aa6e67a (pc 
> 0x55901aa6e67a bp 0x7fff0ac087e0 sp 0x7fff0ac087a0 T0)
> #0 0x55901aa6e67a in npcm7xx_adc_convert /hw/adc/npcm7xx_adc.c:60:51
> #1 0x55901aa6e67a in npcm7xx_adc_convert_done /hw/adc/npcm7xx_adc.c:106:15
> #2 0x55901ceb847e in timerlist_run_timers /util/qemu-timer.c:574:9
> #3 0x55901c05d804 in qtest_clock_warp /softmmu/qtest.c:356:9
> #4 0x55901c059781 in qtest_process_command /softmmu/qtest.c:752:9
> #5 0x55901c051b97 in qtest_process_inbuf /softmmu/qtest.c:797:9
> #6 0x55901c8a2286 in fd_chr_read /chardev/char-fd.c:68:9
> #7 0x7fa5c43f1aae in g_main_context_dispatch 
> (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x51aae)
> #8 0x55901cefd363 in glib_pollfds_poll /util/main-loop.c:232:9
> #9 0x55901cefd363 in os_host_main_loop_wait /util/main-loop.c:255:5
> #10 0x55901cefd363 in main_loop_wait /util/main-loop.c:531:11
> #11 0x55901bfb8599 in qemu_main_loop /softmmu/runstate.c:721:9
> #12 0x55901a2451fd in main /softmmu/main.c:50:5
> #13 0x7fa5c3e96cc9 in __libc_start_main csu/../csu/libc-start.c:308:16
> #14 0x55901a198bc9 in _start 
> (/home/alxndr/Development/qemu/build/qemu-system-aarch64+0x3350bc9)
> 
> AddressSanitizer can not provide additional info.
> SUMMARY: AddressSanitizer: FPE /hw/adc/npcm7xx_adc.c:60:51 in 
> npcm7xx_adc_convert

The ADC realization in npcm7xx_realize is incomplete, vref/iref
properties are not set, thus 0.

Looking at the qtests (npcm7xx_adc-test.c) these are set via
'qom-set' QMP calls.

Assuming vref/iref are constant on a board, shouldn't we have
a npcm7xx_adc_realize() method checking these properties are
set, returning a proper error message if not?

Thanks,

Phil.