[PATCH] [BUGFIX] kprobes/x86: Release insn_slot in failure path

[Masami Hiramatsu]

The commit 003002e04ed3 ("kprobes: Fix arch_prepare_kprobe
to handle copy insn failures") returns error if copying
insn failed, but not release allocated insn_slot.

Release insn_slot assigned to ainsn.slot correctly if
copy insn is failed.

Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
Fixes: 003002e04ed3 ("kprobes: Fix arch_prepare_kprobe to handle copy insn 
failures")
---
 arch/x86/kernel/kprobes/core.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 6b87780..f015371 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -457,6 +457,8 @@ static int arch_copy_kprobe(struct kprobe *p)
 
 int arch_prepare_kprobe(struct kprobe *p)
 {
+       int ret;
+
        if (alternatives_text_reserved(p->addr, p->addr))
                return -EINVAL;
 
@@ -467,7 +469,13 @@ int arch_prepare_kprobe(struct kprobe *p)
        if (!p->ainsn.insn)
                return -ENOMEM;
 
-       return arch_copy_kprobe(p);
+       ret = arch_copy_kprobe(p);
+       if (ret) {
+               free_insn_slot(p->ainsn.insn, 0);
+               p->ainsn.insn = NULL;
+       }
+
+       return ret;
 }
 
 void arch_arm_kprobe(struct kprobe *p)