From: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Date: Fri, 29 Jun 2018 12:48:20 +0000 (+0200)
Subject: bpf: hash map: decrement counter on error
X-Git-Tag: v4.17.19~147
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ba80c24ebc85ced0d9efe83b73651558f67bce56;p=thirdparty%2Fkernel%2Fstable.git

bpf: hash map: decrement counter on error

[ Upstream commit ed2b82c03dc187018307c7c6bf9299705f3db383 ]

Decrement the number of elements in the map in case the allocation
of a new node fails.

Fixes: 6c9059817432 ("bpf: pre-allocate hash map elements")
Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index b76828f23b49a..3bd61b004418d 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -743,13 +743,15 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 				 * old element will be freed immediately.
 				 * Otherwise return an error
 				 */
-				atomic_dec(&htab->count);
-				return ERR_PTR(-E2BIG);
+				l_new = ERR_PTR(-E2BIG);
+				goto dec_count;
 			}
 		l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
 				     htab->map.numa_node);
-		if (!l_new)
-			return ERR_PTR(-ENOMEM);
+		if (!l_new) {
+			l_new = ERR_PTR(-ENOMEM);
+			goto dec_count;
+		}
 	}
 
 	memcpy(l_new->key, key, key_size);
@@ -762,7 +764,8 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 						  GFP_ATOMIC | __GFP_NOWARN);
 			if (!pptr) {
 				kfree(l_new);
-				return ERR_PTR(-ENOMEM);
+				l_new = ERR_PTR(-ENOMEM);
+				goto dec_count;
 			}
 		}
 
@@ -776,6 +779,9 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 
 	l_new->hash = hash;
 	return l_new;
+dec_count:
+	atomic_dec(&htab->count);
+	return l_new;
 }
 
 static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,