Re: [PATCH] kprobes/x86: opt: free optinsn cache when range check fails

From: Wang Nan
Date: Wed Aug 27 2014 - 08:16:21 EST


On 2014/7/29 9:43, Masami Hiramatsu wrote:
> (2014/07/28 21:20), Wang Nan wrote:
>> This patch frees optinsn slot when range check error to prevent memory
>> leaks. Before this patch, cache entry in kprobe_insn_cache won't be
>> freed if kprobe optimizing fails due to range check failure.
>>
>> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
>
> Oops, thank you for finding it!
>
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
>

Hi Masami Hiramatsu,

I don't find this patch in newest upstream. Is there any problem?

> BTW, would you really have hit this error?
> I'd like to know the case if this really happens.
>
>> ---
>> arch/x86/kernel/kprobes/opt.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
>> index f304773..f1314d0 100644
>> --- a/arch/x86/kernel/kprobes/opt.c
>> +++ b/arch/x86/kernel/kprobes/opt.c
>> @@ -338,8 +338,10 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op)
>> * a relative jump.
>> */
>> rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE;
>> - if (abs(rel) > 0x7fffffff)
>> + if (abs(rel) > 0x7fffffff) {
>> + __arch_remove_optimized_kprobe(op, 0);
>> return -ERANGE;
>> + }
>>
>> buf = (u8 *)op->optinsn.insn;
>>
>>
>
>


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