Uprobe: fix NULL dereference on x86

When uprobe_handler_part2() is called, it dereferences
pre_handler callback without any check, but
uprobe_handler_part2() is called itself from
uprobe_handler_atomic() when pre_handler is NULL.

Change-Id: Ia4cdbdc20c50aa3d891c790eea3545da06506f47
Signed-off-by: Alexander Aksenov <a.aksenov@samsung.com>

diff --git a/uprobe/arch/x86/swap-asm/swap_uprobes.c b/uprobe/arch/x86/swap-asm/swap_uprobes.c
index 99308bc..28de890 100644 (file)
--- a/uprobe/arch/x86/swap-asm/swap_uprobes.c
+++ b/uprobe/arch/x86/swap-asm/swap_uprobes.c
@@ -549,7 +549,7 @@ static int uprobe_handler_retprobe(struct uprobe *p, struct pt_regs *regs)
 
 static int uprobe_handler_part2(struct uprobe *p, struct pt_regs *regs)
 {
-       if (!p->pre_handler(p, regs)) {
+       if (p->pre_handler && !p->pre_handler(p, regs)) {
                prepare_tramp(p, regs);
                if (p->ainsn.boostable == 1 && !p->post_handler)
                        goto exit_and_put_up;