uprobes/x86: Don't change the task's state if ->pre_xol() fails

Currently this doesn't matter, the only ->pre_xol() hook can't fail,
but we need to fix arch_uprobe_pre_xol() anyway. If ->pre_xol() fails
we should not change regs->ip/flags, we should just return the error
to make restart actually possible.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index ecbffd16d090..f4464b1b9435 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -687,6 +687,12 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
         struct uprobe_task *utask = current->utask;
 
+        if (auprobe->ops->pre_xol) {
+                int err = auprobe->ops->pre_xol(auprobe, regs);
+                if (err)
+                        return err;
+        }
+
         regs->ip = utask->xol_vaddr;
         utask->autask.saved_trap_nr = current->thread.trap_nr;
         current->thread.trap_nr = UPROBE_TRAP_NR;
@@ -696,8 +702,6 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
         if (test_tsk_thread_flag(current, TIF_BLOCKSTEP))
                 set_task_blockstep(current, false);
 
-        if (auprobe->ops->pre_xol)
-                return auprobe->ops->pre_xol(auprobe, regs);
         return 0;
 }