Re: [PATCH] kallsyms: Fix segfault in prefix_underscores_count().

[Li Zefan <lizf@cn.fujitsu.com>]

>> But..as the name "prefix_underscores_count" suggests, shouldn't
>> it be:
>> 	while (*tail == '_')
>> 		tail++;
>> ??
>>
> Yes, that was what I did initially as well, but the behaviour is not
> exactly the same, and I wanted an explanation from Lai if there were some
> other intentions for the code. In any event, simplifying it still manages
> to do the right thing, so I'm fine with that.
> 

I know what happened.

Lai sent this patch:
	http://lkml.org/lkml/2009/3/13/72

And he himself found the bug, and fixed it and resent it:
	http://lkml.org/lkml/2009/3/13/156

But Andrew mistakenly picked up the former one.

> ------------------------
> Subject: [PATCH] kallsyms: Fix segfault in prefix_underscores_count().
> 
> Commit b478b782e110fdb4135caa3062b6d687e989d994 "kallsyms, tracing:
> output more proper symbol name" introduces a "bugfix" that introduces
> a segfault in kallsyms in my configurations.
> 
> The cause is the introduction of prefix_underscores_count() which
> attempts to count underscores, even in symbols that do not have them.
> As a result, it just uselessly runs past the end of the buffer until it
> crashes:
> 
>   CC      init/version.o
>   LD      init/built-in.o
>   LD      .tmp_vmlinux1
>   KSYM    .tmp_kallsyms1.S
> /bin/sh: line 1: 16934 Done                    sh-linux-gnu-nm -n .tmp_vmlinux1
>      16935 Segmentation fault      | scripts/kallsyms > .tmp_kallsyms1.S
> make: *** [.tmp_kallsyms1.S] Error 139
> 
> This simplifies the logic and just does a straightforward count.
> 
> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
> 

Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>