* [PATCH] tracepoint: don't make assumptions about length of string on task rename
@ 2015-08-28 11:06 Sasha Levin
2015-08-28 15:02 ` Steven Rostedt
0 siblings, 1 reply; 4+ messages in thread
From: Sasha Levin @ 2015-08-28 11:06 UTC (permalink / raw)
To: rostedt, mingo; +Cc: linux-kernel, Sasha Levin
While the dest comm string size is assured to be at least TASK_COMM_LEN long,
doing a memcpy() also adds the assumption that the source is at least that
long as well, which isn't assured, and isn't true in cases such as:
set_task_comm(worker->task, "kworker/dying");
This leads to accessing invalid memory.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
include/trace/events/task.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/trace/events/task.h b/include/trace/events/task.h
index dee3bb1..2cca6cd 100644
--- a/include/trace/events/task.h
+++ b/include/trace/events/task.h
@@ -46,7 +46,7 @@ TRACE_EVENT(task_rename,
TP_fast_assign(
__entry->pid = task->pid;
memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
- memcpy(entry->newcomm, comm, TASK_COMM_LEN);
+ strlcpy(entry->newcomm, comm, TASK_COMM_LEN);
__entry->oom_score_adj = task->signal->oom_score_adj;
),
--
1.7.10.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] tracepoint: don't make assumptions about length of string on task rename
2015-08-28 11:06 [PATCH] tracepoint: don't make assumptions about length of string on task rename Sasha Levin
@ 2015-08-28 15:02 ` Steven Rostedt
2015-09-01 15:07 ` Sasha Levin
0 siblings, 1 reply; 4+ messages in thread
From: Steven Rostedt @ 2015-08-28 15:02 UTC (permalink / raw)
To: Sasha Levin; +Cc: mingo, linux-kernel
On Fri, 28 Aug 2015 07:06:58 -0400
Sasha Levin <sasha.levin@oracle.com> wrote:
> While the dest comm string size is assured to be at least TASK_COMM_LEN long,
> doing a memcpy() also adds the assumption that the source is at least that
> long as well, which isn't assured, and isn't true in cases such as:
>
> set_task_comm(worker->task, "kworker/dying");
>
> This leads to accessing invalid memory.
>
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Should this go to stable as well?
Also, as the memcpy was just faster than a strcpy, the static length
was used. Perhaps we should convert that to a dynamic length string.
But that should be a separate patch as this one fixes a possible bug,
and the conversion to a dynamic string is just an enhancement.
-- Steve
> ---
> include/trace/events/task.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/trace/events/task.h b/include/trace/events/task.h
> index dee3bb1..2cca6cd 100644
> --- a/include/trace/events/task.h
> +++ b/include/trace/events/task.h
> @@ -46,7 +46,7 @@ TRACE_EVENT(task_rename,
> TP_fast_assign(
> __entry->pid = task->pid;
> memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
> - memcpy(entry->newcomm, comm, TASK_COMM_LEN);
> + strlcpy(entry->newcomm, comm, TASK_COMM_LEN);
> __entry->oom_score_adj = task->signal->oom_score_adj;
> ),
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tracepoint: don't make assumptions about length of string on task rename
2015-08-28 15:02 ` Steven Rostedt
@ 2015-09-01 15:07 ` Sasha Levin
2015-09-01 15:32 ` Steven Rostedt
0 siblings, 1 reply; 4+ messages in thread
From: Sasha Levin @ 2015-09-01 15:07 UTC (permalink / raw)
To: Steven Rostedt; +Cc: mingo, linux-kernel
On 08/28/2015 11:02 AM, Steven Rostedt wrote:
> On Fri, 28 Aug 2015 07:06:58 -0400
> Sasha Levin <sasha.levin@oracle.com> wrote:
>
>> While the dest comm string size is assured to be at least TASK_COMM_LEN long,
>> doing a memcpy() also adds the assumption that the source is at least that
>> long as well, which isn't assured, and isn't true in cases such as:
>>
>> set_task_comm(worker->task, "kworker/dying");
>>
>> This leads to accessing invalid memory.
>>
>> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
>
> Acked-by: Steven Rostedt <rostedt@goodmis.org>
>
> Should this go to stable as well?
Yup.
> Also, as the memcpy was just faster than a strcpy, the static length
> was used. Perhaps we should convert that to a dynamic length string.
> But that should be a separate patch as this one fixes a possible bug,
> and the conversion to a dynamic string is just an enhancement.
That'll slow things down for the common case, no?
Thanks,
Sasha
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tracepoint: don't make assumptions about length of string on task rename
2015-09-01 15:07 ` Sasha Levin
@ 2015-09-01 15:32 ` Steven Rostedt
0 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2015-09-01 15:32 UTC (permalink / raw)
To: Sasha Levin; +Cc: mingo, linux-kernel
On Tue, 01 Sep 2015 11:07:32 -0400
Sasha Levin <sasha.levin@oracle.com> wrote:
> > Also, as the memcpy was just faster than a strcpy, the static length
> > was used. Perhaps we should convert that to a dynamic length string.
> > But that should be a separate patch as this one fixes a possible bug,
> > and the conversion to a dynamic string is just an enhancement.
>
> That'll slow things down for the common case, no?
Not really that much.
The comms should have been dynamic strings too, but the sched_switch
tracepoint (the one others have been copied from) was created before we
had dynamic strings for tracepoints.
-- Steve
^ permalink raw reply [flat|nested] 4+ messages in thread
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2015-08-28 11:06 [PATCH] tracepoint: don't make assumptions about length of string on task rename Sasha Levin
2015-08-28 15:02 ` Steven Rostedt
2015-09-01 15:07 ` Sasha Levin
2015-09-01 15:32 ` Steven Rostedt
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