uprobes: Change uprobe_copy_process() to dup return_instances
uprobe_copy_process() assumes that the new child doesn't need ->utask, it should be allocated by demand. But this is not true if the forking task has the pending ret- probes, the child should report them as well and thus it needs the copy of parent's ->return_instances chain. Otherwise the child crashes when it returns from the probed function. Alternatively we could cleanup the child's stack, but this needs per-arch changes and this is not what we want. At least systemtap expects a .return in the child too. Note: this change alone doesn't fix the problem, see the next change. Reported-by: Martin Cermak <mcermak@redhat.com> Reported-by: David Smith <dsmith@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
This commit is contained in:
parent
af0d95af79
commit
248d3a7b2f
kernel/events
|
@ -1366,12 +1366,55 @@ static struct uprobe_task *get_utask(void)
|
||||||
return current->utask;
|
return current->utask;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)
|
||||||
|
{
|
||||||
|
struct uprobe_task *n_utask;
|
||||||
|
struct return_instance **p, *o, *n;
|
||||||
|
|
||||||
|
n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
|
||||||
|
if (!n_utask)
|
||||||
|
return -ENOMEM;
|
||||||
|
t->utask = n_utask;
|
||||||
|
|
||||||
|
p = &n_utask->return_instances;
|
||||||
|
for (o = o_utask->return_instances; o; o = o->next) {
|
||||||
|
n = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
|
||||||
|
if (!n)
|
||||||
|
return -ENOMEM;
|
||||||
|
|
||||||
|
*n = *o;
|
||||||
|
atomic_inc(&n->uprobe->ref);
|
||||||
|
n->next = NULL;
|
||||||
|
|
||||||
|
*p = n;
|
||||||
|
p = &n->next;
|
||||||
|
n_utask->depth++;
|
||||||
|
}
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
static void uprobe_warn(struct task_struct *t, const char *msg)
|
||||||
|
{
|
||||||
|
pr_warn("uprobe: %s:%d failed to %s\n",
|
||||||
|
current->comm, current->pid, msg);
|
||||||
|
}
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* Called in context of a new clone/fork from copy_process.
|
* Called in context of a new clone/fork from copy_process.
|
||||||
*/
|
*/
|
||||||
void uprobe_copy_process(struct task_struct *t)
|
void uprobe_copy_process(struct task_struct *t)
|
||||||
{
|
{
|
||||||
|
struct uprobe_task *utask = current->utask;
|
||||||
|
struct mm_struct *mm = current->mm;
|
||||||
|
|
||||||
t->utask = NULL;
|
t->utask = NULL;
|
||||||
|
|
||||||
|
if (mm == t->mm || !utask || !utask->return_instances)
|
||||||
|
return;
|
||||||
|
|
||||||
|
if (dup_utask(t, utask))
|
||||||
|
return uprobe_warn(t, "dup ret instances");
|
||||||
}
|
}
|
||||||
|
|
||||||
/*
|
/*
|
||||||
|
|
Loading…
Reference in New Issue