Re: [PATCH][RESEND] kprobes: initialize before using a hlist

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

(2012/01/10 9:47), Jim Keniston wrote:
> On Mon, 2012-01-09 at 13:50 +0530, Ananth N Mavinakayanahalli wrote:
>> From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
>>
>> Commit ef53d9c5e introduced a bug where we can potentially leak
>> kretprobe_instances since we initialize a hlist head after having
>> used it.
>>
>> Initialize the hlist head before using it.
>>
>> (Resent with correct email ID for -stable)
>>
>> Reported by: Jim Keniston <jkenisto@us.ibm.com>
>> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>> Cc: <stable@vger.kernel.org>
> 
> Acked-by: Jim Keniston <jkenisto@us.ibm.com>

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Thank you!

> 
>> ---
>>  kernel/kprobes.c |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Index: linux-3.2/kernel/kprobes.c
>> ===================================================================
>> --- linux-3.2.orig/kernel/kprobes.c
>> +++ linux-3.2/kernel/kprobes.c
>> @@ -1077,6 +1077,7 @@ void __kprobes kprobe_flush_task(struct 
>>  		/* Early boot.  kretprobe_table_locks not yet initialized. */
>>  		return;
>>
>> +	INIT_HLIST_HEAD(&empty_rp);
>>  	hash = hash_ptr(tk, KPROBE_HASH_BITS);
>>  	head = &kretprobe_inst_table[hash];
>>  	kretprobe_table_lock(hash, &flags);
>> @@ -1085,7 +1086,6 @@ void __kprobes kprobe_flush_task(struct 
>>  			recycle_rp_inst(ri, &empty_rp);
>>  	}
>>  	kretprobe_table_unlock(hash, &flags);
>> -	INIT_HLIST_HEAD(&empty_rp);
>>  	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
>>  		hlist_del(&ri->hlist);
>>  		kfree(ri);
> 
> 
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-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com