[Crash-utility] [PATCH] Fixed the segment fault when ikconfig passed nonstandard values

[刘云]

在 2021/1/5 上午7:21, HAGIO KAZUHITO(萩尾 一仁) 写道:
> Hi Jackie, Hatayama san,
>
> -----Original Message-----
>> 在 2021/1/4 下午1:00, d.hatayama at fujitsu.com 写道:
>>>>> Some strange reasons may cause kcore to collect some strange
>>>>> entries of ikconfig, such as CONFIG_SECU+[some hex data] causes
>>>> Could you tell me the example of such CONFIG_SEC+[some hex data] that
>>>> causes the val to have NULL. I tried to reproduce but failed.
>>
>> It's hard to say about that, because It's just appeared in the virtual
>> machine, when I debug
>>
>> with vmcore (Not a dump.xxx file in my memory).
>>
>>
>> Ubuntu-kernel/debian/rules.d/2-binary-arch.mk has that:
>>
>> $(stampdir)/stamp-prepare-tree-%: $(archconfdir)/kylinos_%_defconfig
>> debian/scripts/fix-filenames
>>           @echo Debug: $@
>>           install -d $(builddir)/build-$*
>>           touch $(builddir)/build-$*/ubuntu-build
>>           [ "$(do_full_source)" != 'true' ] && true || \
>>                   rsync -a --exclude debian --exclude debian.master
>> --exclude $(DEBIAN) * $(builddir)/build-$*
>>           cat $(wordlist 1,3,$^) | sed -e
>> 's/.*CONFIG_VERSION_SIGNATURE.*/CONFIG_VERSION_SIGNATURE="KYLINOS
>> $(release)-$(revision)-$* $(raw_kernelversion)"/' >
>> $(builddir)/build-$*/.config
>>           find $(builddir)/build-$* -name "*.ko" | xargs rm -f
>>           $(build_cd) $(kmake) $(build_O) -j1 olddefconfig syncconfig
>> prepare scripts
>>           touch $@
>>
>> Every time,  '.config' has object file 'fix-filenames' hex data with
>> config, maybe that is an reason, but
>>
>> I'm not sure. Maybe It's just any other strange reason cause
>> /proc/vmcore has CONFIG_SECU+[hex data].
>>
>>> I guess you mean CONFIG_SECU+[some hex data] to be **strings that don't
>>> contain the delimitor string '='** and then strtok_r() interprets
>>> it as consisting of a single token, hence val resulting in having NULL.
>>> If so, I think it's better to write so.
> (Thanks for the comment.)
>
>>
>> Yes, It is.
> Could you add more words like the above "entries that do not contain
> the delimiter string '='" to the commit message?

OK, I will send v2 with your suggest and hatayama's comment.

Thanks. BR, Jackie Liu

>
>>
>>> OTOH, due to the cause of this issue, is there also possibility
>>> that the broken line contains two or more '=' and broken name
>>> and values are appended in the ikconfig list? It has to be less
>>> important than here because it doesn't result in segfault, but
>>> it might be necessary to deal with it too depending on its actual impact.
> Two or more '=' characters except for the first one will be added to
> the value.  It can be an arbitrary string, so I think it would be hard
> to check if a value is valid or not here.
>
> If we check it, we should do when using the value.  But I don't think
> the entries that crash uses can break easily..
>
> Thanks,
> Kazu
>