uprobes: Teach uprobe_copy_process() to handle CLONE_VFORK
uprobe_copy_process() does nothing if the child shares ->mm with
the forking process, but there is a special case: CLONE_VFORK.
In this case it would be more correct to do dup_utask() but avoid
dup_xol(). This is not that important, the child should not unwind
its stack too much, this can corrupt the parent's stack, but at
least we need this to allow to ret-probe __vfork() itself.
Note: in theory, it would be better to check task_pt_regs(p)->sp
instead of CLONE_VFORK, we need to dup_utask() if and only if the
child can return from the function called by the parent. But this
needs the arch-dependant helper, and I think that nobody actually
does clone(same_stack, CLONE_VM).
Reported-by: Martin Cermak <mcermak@redhat.com>
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index e6fba62..9e0d5a6 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -117,7 +117,7 @@
extern void uprobe_end_dup_mmap(void);
extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm);
extern void uprobe_free_utask(struct task_struct *t);
-extern void uprobe_copy_process(struct task_struct *t);
+extern void uprobe_copy_process(struct task_struct *t, unsigned long flags);
extern unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs);
extern int uprobe_post_sstep_notifier(struct pt_regs *regs);
extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
@@ -174,7 +174,7 @@
static inline void uprobe_free_utask(struct task_struct *t)
{
}
-static inline void uprobe_copy_process(struct task_struct *t)
+static inline void uprobe_copy_process(struct task_struct *t, unsigned long flags)
{
}
static inline void uprobe_clear_state(struct mm_struct *mm)