Re: null iv parameter passed to combo_init()

On Sun, Jan 9, 2022 at 12:38 PM Zhihong Yu <zyu(at)yugabyte(dot)com> wrote:

>
>
> On Sun, Jan 9, 2022 at 8:48 AM Noah Misch <noah(at)leadboat(dot)com> wrote:
>
>> On Sun, Jan 09, 2022 at 04:37:32AM -0800, Zhihong Yu wrote:
>> > On Sat, Jan 8, 2022 at 11:32 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> > > Noah Misch <noah(at)leadboat(dot)com> writes:
>> > > > On further thought, I would write it this way:
>> > >
>> > > > - else
>> > > > + else if (ivlen != 0)
>> > > > memcpy(ivbuf, iv, ivlen);
>> > >
>> > > FWIW, I liked the "ivlen > 0" formulation better. They should be
>> > > equivalent, because ivlen is unsigned, but it just seems like "> 0"
>> > > is more natural.
>>
>> If I were considering the one code site in isolation, I'd pick "ivlen >
>> 0".
>> But of the four sites identified so far, three have signed length
>> variables.
>> Since we're likely to get more examples of this pattern, some signed and
>> some
>> unsigned, I'd rather use a style that does the optimal thing whether or
>> not
>> the variable is signed. What do you think?
>>
>> > Patch v4 is attached.
>>
>> Does this pass the test procedure shown upthread?
>>
> Hi,
> I installed gcc 4.9.3
>
> When I ran:
> ./configure CFLAGS='-fsanitize=undefined
> -fsanitize-undefined-trap-on-error'
>
> I saw:
>
> configure:3977: $? = 0
> configure:3966: gcc -V >&5
> gcc: error: unrecognized command line option '-V'
> gcc: fatal error: no input files
> compilation terminated.
> configure:3977: $? = 1
> configure:3966: gcc -qversion >&5
> gcc: error: unrecognized command line option '-qversion'
> gcc: fatal error: no input files
> compilation terminated.
> configure:3977: $? = 1
> configure:3997: checking whether the C compiler works
> configure:4019: gcc -fsanitize=undefined
> -fsanitize-undefined-trap-on-error conftest.c >&5
> gcc: error: unrecognized command line option
> '-fsanitize-undefined-trap-on-error'
> configure:4023: $? = 1
> configure:4061: result: no
>
> I wonder if a higher version gcc is needed.
>
> FYI
>

After installing gcc-11, ./configure passed (with 0003-memcpy-null.patch).
In the output of `make check-world`, I don't see `runtime error`.
Though there was a crash (maybe specific to my machine):

Core was generated by
`/nfusr/dev-server/zyu/postgres/tmp_install/usr/local/pgsql/bin/postgres
--singl'.
Program terminated with signal SIGILL, Illegal instruction.
#0 0x000000000050642d in write_item.cold ()
Missing separate debuginfos, use: debuginfo-install
glibc-2.17-325.el7_9.x86_64 nss-pam-ldapd-0.8.13-25.el7.x86_64
sssd-client-1.16.5-10.el7_9.10.x86_64
(gdb) bt
#0 0x000000000050642d in write_item.cold ()
#1 0x0000000000ba9d1b in write_relcache_init_file ()
#2 0x0000000000bb58f7 in RelationCacheInitializePhase3 ()
#3 0x0000000000bd5cb5 in InitPostgres ()
#4 0x0000000000a0a9ea in PostgresMain ()

FYI