lkml.org 
[lkml]   [2018]   [Jul]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v5 09/10] Uprobes/sdt: Document about reference counter
From
Date
Hi Srikar,

On 07/02/2018 08:24 PM, Srikar Dronamraju wrote:
> * Ravi Bangoria <ravi.bangoria@linux.ibm.com> [2018-06-28 10:52:08]:
>
>> Reference counter gate the invocation of probe. If present,
>> by default reference count is 0. Kernel needs to increment
>> it before tracing the probe and decrement it when done. This
>> is identical to semaphore in Userspace Statically Defined
>> Tracepoints (USDT).
>>
>> Document usage of reference counter.
>>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
>
> Unlike perf, this mechanism cannot detect ref count and depends on the
> users data. What happens if the user mistakenly provides a wrong location?
> I guess he can corrupt some other data structures?

Yes, if user is giving wrong ref_ctr_offset, uprobe infrastructure will
corrupt some user data.

>
> Hence I would think twice of advertising this mechanism. i.e keep this
> as an undocumented feature.
>

I don't mind.

Thanks,
Ravi

\
 
 \ /
  Last update: 2018-07-03 09:51    [W:0.081 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site