Messages in this thread | | | Date | Wed, 23 Jan 2008 22:07:42 +0300 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH 1/6] POWERPC: use KSYM_NAME_LEN |
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[Paulo Marques - Wed, Jan 23, 2008 at 06:59:09PM +0000] > Cyrill Gorcunov wrote: >> [Paulo Marques - Wed, Jan 23, 2008 at 06:26:28PM +0000] >>> Cyrill Gorcunov wrote: >>>> [...] >>>> case 's': >>>> - getstring(tmp, 64); >>>> + getstring(tmp, sizeof(tmp)); >>>> if (setjmp(bus_error_jmp) == 0) { >>>> catch_memory_errors = 1; >>>> sync(); >> just after that poin in the original code a call to kallsyms_lookup_name >> is done - so i think it could be an overflow (of course it depends >> on what *exactly* the name is being searched, and Paulo - I didn't >> managed to get *the whole picture* of what is going on in this >> code - so the thoughs were like: kallsyms_lookup_name could find >> a quite long name restricted by KSYM_NAME_LEN (dunno how it could >> happens - due to buggy code or due to memory corruption outside, >> it does not matter - the only matter - it *could* find that long >> name). > > Ah, now I understand your confusion: kallsyms_lookup_name doesn't fill the > name. It searches the name and returns the address. It is the _caller_ that > fills the name, not kallsyms_lookup_name. > > It is used for stuff like: "give me the address of function foo": > addr = kallsyms_lookup_name("foo"); >
oh my, how could I oversight that... damn!!! my bad!!!
>> Anyway - it's just an attempt ;) we always could drop it far-far away ;) > > I think that using KSYM_NAME_LEN would be a nice cleanup for xmon, but it > is for the powerpc guys to decide if they want to do it. I just wanted to > point the change in behavior so that it wouldn't go unnoticed.
thanks, it's really important
> > For all we know, the stack may at that point be close to full and an extra > 64 bytes may tip it over the edge. >
oops, thanks for pointing out
>>> This also introduces a change in behavior. It is still a nice cleanup, >>> though. So, if the powerpc people feel they can spare an extra 64 bytes >>> of stack here, I guess it's ok. >> Thanks a lot for review Paulo! > > No problem. I always keep an eye out for kallsyms related stuff.
;)
> > -- > Paulo Marques - www.grupopie.com > > "There cannot be a crisis today; my schedule is already full." > - Cyrill -
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