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perf counters: group counter, fixes
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Impact: bugfix

Check that a group does not span outside the context of a CPU or a task.

Also, do not allow deep recursive hierarchies.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Ingo Molnar committed Dec 11, 2008
1 parent 04289bb commit ccff286
Showing 1 changed file with 20 additions and 19 deletions.
39 changes: 20 additions & 19 deletions kernel/perf_counter.c
Original file line number Diff line number Diff line change
Expand Up @@ -107,9 +107,6 @@ list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx)

list_del_init(&counter->list_entry);

if (list_empty(&counter->sibling_list))
return;

/*
* If this was a group counter with sibling counters then
* upgrade the siblings to singleton counters by adding them
Expand Down Expand Up @@ -395,9 +392,6 @@ counter_sched_in(struct perf_counter *counter,
struct perf_counter_context *ctx,
int cpu)
{
if (!counter->active)
return;

hw_perf_counter_enable(counter);
counter->active = 1;
counter->oncpu = cpu; /* TODO: put 'cpu' into cpuctx->cpu */
Expand Down Expand Up @@ -876,32 +870,39 @@ asmlinkage int sys_perf_counter_open(
return -EFAULT;

/*
* Look up the group leader:
* Get the target context (task or percpu):
*/
ctx = find_get_context(pid, cpu);
if (IS_ERR(ctx))
return PTR_ERR(ctx);

/*
* Look up the group leader (we will attach this counter to it):
*/
group_leader = NULL;
if (group_fd != -1) {
ret = -EINVAL;
group_file = fget_light(group_fd, &fput_needed);
if (!group_file)
goto out_fput;
goto err_put_context;
if (group_file->f_op != &perf_fops)
goto out_fput;
goto err_put_context;

group_leader = group_file->private_data;
/*
* Do not allow a recursive hierarchy:
* Do not allow a recursive hierarchy (this new sibling
* becoming part of another group-sibling):
*/
if (group_leader->group_leader != group_leader)
goto err_put_context;
/*
* Do not allow to attach to a group in a different
* task or CPU context:
*/
if (group_leader->group_leader)
goto out_fput;
if (group_leader->ctx != ctx)
goto err_put_context;
}

/*
* Get the target context (task or percpu):
*/
ctx = find_get_context(pid, cpu);
if (IS_ERR(ctx))
return PTR_ERR(ctx);

ret = -ENOMEM;
counter = perf_counter_alloc(&hw_event, cpu, group_leader);
if (!counter)
Expand Down

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