linux-kernel - [PATCH v2] bpf: Fix integer overflow in argument calculation for bpf_map_area

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Message-Id: <20210613143440.71975-1-minhquangbui99@gmail.com>
Date:   Sun, 13 Jun 2021 21:34:39 +0700
From:   Bui Quang Minh <minhquangbui99@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     minhquangbui99@...il.com, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        KP Singh <kpsingh@...nel.org>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Lorenz Bauer <lmb@...udflare.com>,
        Roman Gushchin <guro@...com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc

In 32-bit architecture, the result of sizeof() is a 32-bit integer so
the expression becomes the multiplication between 2 32-bit integer which
can potentially leads to integer overflow. As a result,
bpf_map_area_alloc() allocates less memory than needed.

Fix this by casting 1 operand to u64.

Fixes: 0d2c4f964050 ("bpf: Eliminate rlimit-based memory accounting for sockmap
and sockhash maps")
Fixes: 99c51064fb06 ("devmap: Use bpf_map_area_alloc() for allocating hash
buckets")
Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references")
Signed-off-by: Bui Quang Minh <minhquangbui99@...il.com>
---
v2: Add Fixes tag

 kernel/bpf/devmap.c | 4 ++--
 net/core/sock_map.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index aa516472ce46..3b45c23286c0 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -92,7 +92,7 @@ static struct hlist_head *dev_map_create_hash(unsigned int entries,
 	int i;
 	struct hlist_head *hash;
 
-	hash = bpf_map_area_alloc(entries * sizeof(*hash), numa_node);
+	hash = bpf_map_area_alloc((u64) entries * sizeof(*hash), numa_node);
 	if (hash != NULL)
 		for (i = 0; i < entries; i++)
 			INIT_HLIST_HEAD(&hash[i]);
@@ -143,7 +143,7 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
 
 		spin_lock_init(&dtab->index_lock);
 	} else {
-		dtab->netdev_map = bpf_map_area_alloc(dtab->map.max_entries *
+		dtab->netdev_map = bpf_map_area_alloc((u64) dtab->map.max_entries *
 						      sizeof(struct bpf_dtab_netdev *),
 						      dtab->map.numa_node);
 		if (!dtab->netdev_map)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 6f1b82b8ad49..60decd6420ca 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -48,7 +48,7 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
 	bpf_map_init_from_attr(&stab->map, attr);
 	raw_spin_lock_init(&stab->lock);
 
-	stab->sks = bpf_map_area_alloc(stab->map.max_entries *
+	stab->sks = bpf_map_area_alloc((u64) stab->map.max_entries *
 				       sizeof(struct sock *),
 				       stab->map.numa_node);
 	if (!stab->sks) {
-- 
2.25.1