Re: [Qemu-devel] clang -fsanitize=undefined warnings in the string visitors

[Peter Maydell]

Ping on this warning issue, since I guess everybody missed it
over Christmas :-)

thanks
-- PMM

On 23 December 2014 at 23:17, Peter Maydell <address@hidden> wrote:
> If you do a clang build with -fsanitize=undefined, then you get some
> sanitizer errors in make check:
>
> TEST: tests/test-string-output-visitor... (pid=31713)
>   /string-visitor/output/int:                                          OK
>   /string-visitor/output/int:                                          OK
>   /string-visitor/output/bool:                                         OK
>   /string-visitor/output/bool:                                         OK
>   /string-visitor/output/number:
> /home/petmay01/linaro/qemu-from-laptop/qemu/qapi/string-output-visitor.c:92:16:OK
>  runtime error: signed integer overflow: 9223372036854775807
> /string-visitor/output/number:                                       +
> 1 cannot be represented in type 'long'
> OK
>   /string-visitor/output/string:                                       OK
> [etc]
>
> and later
> TEST: tests/test-visitor-serialization... (pid=31729)
> [etc]
>   /visitor/serialization/String/primitives/boolean_true2:              OK
>   /visitor/serialization/String/primitives/boolean_true3:              OK
>   /visitor/serialization/String/primitives/boolean_false1:             OK
>   /visitor/serialization/String/primitives/boolean_false2:
> /home/petmay01/linaro/qemu-from-laptop/qemu/qapi/string-output-visitor.c:83:16:OK
>   /visitor/serialization/String/primitives/number_sanity1:
>  runtime error: signed integer overflow: 9223372036854775807 + 1
> cannot be represented in type OK
> 'long'
>   /visitor/serialization/String/primitives/number_sanity2:
> /home/petmay01/linaro/qemu-from-laptop/qemu/qapi/string-input-visitor.c:58:34:OK
>  runtime error: signed integer overflow:
> /visitor/serialization/String/primitives/number_min:
> 9223372036854775807 + 1 cannot be represented in type 'long long'
> OK
> /home/petmay01/linaro/qemu-from-laptop/qemu/qapi/string-input-visitor.c:216:13:
> runtime error:   /visitor/serialization/String/primitives/number_max:
>                signed integer overflow: 9223372036854775807 + 1 cannot
> be represented in type 'int64_t' (aka 'long')
> OK
>   /visitor/serialization/String/primitives/integer_sanity1:            OK
>   /visitor/serialization/String/primitives/integer_sanity2:            OK
> [etc]
>
> You can also see these without clang if you run under gdb and put in
> appropriate conditional breakpoints (eg string_output_append_range()
> with condition (e > 50000). Sample backtrace:
>
> (gdb) bt
> #0  string_output_append_range (sov=0x5555557adbc0,
> s=9223372036854775806, e=9223372036854775807)
>     at 
> /home/petmay01/linaro/qemu-from-laptop/qemu/qapi/string-output-visitor.c:89
> #1  0x000055555558285c in print_type_int (v=0x5555557adbc0,
> obj=0x5555557adec0, name=0x0, errp=0x7fffffffdec8)
>     at 
> /home/petmay01/linaro/qemu-from-laptop/qemu/qapi/string-output-visitor.c:158
> #2  0x00005555555800ab in visit_type_int (v=0x5555557adbc0,
> obj=0x5555557adec0, name=0x0, errp=0x7fffffffdec8)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qapi/qapi-visit-core.c:100
> #3  0x000055555555e73f in visit_type_intList (m=0x5555557adbc0,
> obj=0x7fffffffdf28, name=0x0, errp=0x7fffffffdf30)
>     at qapi-visit.c:57
> #4  0x0000555555558263 in test_visitor_out_intList
> (data=0x5555557adb30, unused=0x7fffffffe350)
>     at 
> /home/petmay01/linaro/qemu-from-laptop/qemu/tests/test-string-output-visitor.c:93
> #5  0x00007ffff7b3ea81 in test_case_run (tc=0x5555557ad500) at
> /build/buildd/glib2.0-2.40.2/./glib/gtestutils.c:2059
> #6  g_test_run_suite_internal (address@hidden,
> address@hidden "")
>     at /build/buildd/glib2.0-2.40.2/./glib/gtestutils.c:2120
> #7  0x00007ffff7b3ec46 in g_test_run_suite_internal
> (address@hidden,
>     address@hidden "") at
> /build/buildd/glib2.0-2.40.2/./glib/gtestutils.c:2131
> #8  0x00007ffff7b3ec46 in g_test_run_suite_internal
> (address@hidden,
>     address@hidden "") at
> /build/buildd/glib2.0-2.40.2/./glib/gtestutils.c:2131
> #9  0x00007ffff7b3ef9b in g_test_run_suite (suite=0x5555557ac820)
>     at /build/buildd/glib2.0-2.40.2/./glib/gtestutils.c:2184
> #10 0x00007ffff7b3efd1 in g_test_run () at
> /build/buildd/glib2.0-2.40.2/./glib/gtestutils.c:1488
> #11 0x0000555555558fee in main (argc=1, argv=0x7fffffffe468)
>     at 
> /home/petmay01/linaro/qemu-from-laptop/qemu/tests/test-string-output-visitor.c:286
>
> and you can see that 'e' is the max 64 bit signed
> integer and we're about to increment it...
>
> Paolo, the file says you wrote this code?
>
> thanks
> -- PMM