From: Daniel Borkmann <daniel@iogearbox.net>
Date: Wed, 22 Aug 2018 18:09:17 +0200
Subject: bpf, sockmap: fix sock hash count in alloc_sock_hash_elem
Patch-mainline: v4.19-rc2
Git-commit: eb29429d81e31b191f3b2bd19cf820279cec6463
References: bsc#1109837

When we try to allocate a new sock hash entry and the allocation
fails, then sock hash map fails to reduce the map element counter,
meaning we keep accounting this element although it was never used.
Fix it by dropping the element counter on error.

Fixes: 81110384441a ("bpf: sockmap, add hash map support")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/bpf/sockmap.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -2251,8 +2251,10 @@ static struct htab_elem *alloc_sock_hash
 	}
 	l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
 			     htab->map.numa_node);
-	if (!l_new)
+	if (!l_new) {
+		atomic_dec(&htab->count);
 		return ERR_PTR(-ENOMEM);
+	}
 
 	memcpy(l_new->key, key, key_size);
 	l_new->sk = sk;