[PATCH net-next 1/2] bpf: don't enable preemption twice in smap_do_verdict

[Daniel Borkmann]

In smap_do_verdict(), the fall-through branch leads to call
preempt_enable() twice for the SK_REDIRECT, which creates an
imbalance. Only enable it for all remaining cases again.

Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support")
Reported-by: Alexei Starovoitov <a...@kernel.org>
Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
---
 kernel/bpf/sockmap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index f7e5e6c..39de541 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -135,7 +135,8 @@ static void smap_do_verdict(struct smap_psock *psock, 
struct sk_buff *skb)
        /* Fall through and free skb otherwise */
        case SK_DROP:
        default:
-               preempt_enable();
+               if (rc != SK_REDIRECT)
+                       preempt_enable();
                kfree_skb(skb);
        }
 }
-- 
1.9.3