bpf, sockmap: fix sock hash count in alloc_sock_hash_elem

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>

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 60ceb0e1fa56b017fc3ee8b5720caf65c301f09f..40c6ef9fc828659a02bb910f9a7645114f609ab4 100644 (file)
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -2269,8 +2269,10 @@ static struct htab_elem *alloc_sock_hash_elem(struct bpf_htab *htab,
        }
        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;