linux-kernel - Re: [PATCH] kprobes: be more permissive when user specifies both symbol name and address

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Date:	Tue, 15 Apr 2014 17:27:07 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Zhan Jianyu <nasa4836@...il.com>
Cc:	ananth@...ibm.com, anil.s.keshavamurthy@...el.com,
	davem@...emloft.net, rdunlap@...radead.org,
	linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	"yrl.pp-manager.tt@...achi.com" <yrl.pp-manager.tt@...achi.com>
Subject: Re: [PATCH] kprobes: be more permissive when user specifies both
 symbol name and address

(2014/04/15 17:11), Zhan Jianyu wrote:
> On Mon, Apr 14, 2014 at 11:00 PM, Masami Hiramatsu
> <masami.hiramatsu.pt@...achi.com> wrote:
>> if (p->addr) {
>>   if (p->symbol) {
>>     sym = kallsyms_lookup(p->addr, ... &offs ...);
>>     if (strcmp(sym,p->symbol) != 0 || offs != p->offset) {
>>       pr_warning("Error! ...");
>>       goto fail;
>>     }
>>   }
>> } else if (p->symbol) {
>>   kprobe_lookup_name(p->symbol_name, addr);
>>   if (!addr)
>>     goto fail;
>> } else
>>   goto fail;
> 
> 
> Hmm, let's clasify all conditions.
> 
> 1. Only symbol, check it, if not found, fail.
> 2. Only address, check it, if not found, fail.
> 3. Both, check address,
>     3.1 not found, fail, because some symbols might have muplitple instances,
>           we don't bother to check symbol name.
>     3.2 found, check if symbol mismatch, if yes, fail.

  Plus, if the p->offset and offs are different, fail too.

> Is this reasonable?  Next mail is a renewed patch following this priciple.

OK, let me see. :)

Thank you,


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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