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![Jonathan Lemon](/assets/img/avatar_default.png)
When kzalloc() failed, NULL was returned to the caller, which
tested the pointer with IS_ERR(), which didn't match, so the
pointer was used later, resulting in a NULL dereference.
Return ERR_PTR(-ENOMEM) instead of NULL.
Reported-by: syzbot+491c1b7565ba9069ecae@syzkaller.appspotmail.com
Fixes: 0402acd683
("xsk: remove AF_XDP socket from map when the socket is released")
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
319 lines
6.9 KiB
C
319 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* XSKMAP used for AF_XDP sockets
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* Copyright(c) 2018 Intel Corporation.
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*/
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#include <linux/bpf.h>
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#include <linux/capability.h>
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#include <net/xdp_sock.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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struct xsk_map {
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struct bpf_map map;
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struct xdp_sock **xsk_map;
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struct list_head __percpu *flush_list;
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spinlock_t lock; /* Synchronize map updates */
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};
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int xsk_map_inc(struct xsk_map *map)
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{
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struct bpf_map *m = &map->map;
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m = bpf_map_inc(m, false);
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return PTR_ERR_OR_ZERO(m);
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}
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void xsk_map_put(struct xsk_map *map)
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{
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bpf_map_put(&map->map);
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}
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static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
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struct xdp_sock **map_entry)
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{
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struct xsk_map_node *node;
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int err;
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node = kzalloc(sizeof(*node), GFP_ATOMIC | __GFP_NOWARN);
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if (!node)
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return ERR_PTR(-ENOMEM);
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err = xsk_map_inc(map);
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if (err) {
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kfree(node);
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return ERR_PTR(err);
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}
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node->map = map;
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node->map_entry = map_entry;
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return node;
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}
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static void xsk_map_node_free(struct xsk_map_node *node)
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{
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xsk_map_put(node->map);
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kfree(node);
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}
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static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
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{
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spin_lock_bh(&xs->map_list_lock);
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list_add_tail(&node->node, &xs->map_list);
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spin_unlock_bh(&xs->map_list_lock);
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}
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static void xsk_map_sock_delete(struct xdp_sock *xs,
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struct xdp_sock **map_entry)
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{
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struct xsk_map_node *n, *tmp;
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spin_lock_bh(&xs->map_list_lock);
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list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
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if (map_entry == n->map_entry) {
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list_del(&n->node);
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xsk_map_node_free(n);
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}
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}
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spin_unlock_bh(&xs->map_list_lock);
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}
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static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
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{
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struct xsk_map *m;
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int cpu, err;
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u64 cost;
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if (!capable(CAP_NET_ADMIN))
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return ERR_PTR(-EPERM);
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if (attr->max_entries == 0 || attr->key_size != 4 ||
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attr->value_size != 4 ||
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attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
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return ERR_PTR(-EINVAL);
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m = kzalloc(sizeof(*m), GFP_USER);
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if (!m)
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return ERR_PTR(-ENOMEM);
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bpf_map_init_from_attr(&m->map, attr);
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spin_lock_init(&m->lock);
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cost = (u64)m->map.max_entries * sizeof(struct xdp_sock *);
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cost += sizeof(struct list_head) * num_possible_cpus();
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/* Notice returns -EPERM on if map size is larger than memlock limit */
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err = bpf_map_charge_init(&m->map.memory, cost);
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if (err)
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goto free_m;
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err = -ENOMEM;
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m->flush_list = alloc_percpu(struct list_head);
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if (!m->flush_list)
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goto free_charge;
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for_each_possible_cpu(cpu)
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INIT_LIST_HEAD(per_cpu_ptr(m->flush_list, cpu));
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m->xsk_map = bpf_map_area_alloc(m->map.max_entries *
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sizeof(struct xdp_sock *),
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m->map.numa_node);
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if (!m->xsk_map)
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goto free_percpu;
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return &m->map;
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free_percpu:
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free_percpu(m->flush_list);
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free_charge:
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bpf_map_charge_finish(&m->map.memory);
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free_m:
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kfree(m);
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return ERR_PTR(err);
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}
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static void xsk_map_free(struct bpf_map *map)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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bpf_clear_redirect_map(map);
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synchronize_net();
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free_percpu(m->flush_list);
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bpf_map_area_free(m->xsk_map);
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kfree(m);
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}
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static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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u32 index = key ? *(u32 *)key : U32_MAX;
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u32 *next = next_key;
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if (index >= m->map.max_entries) {
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*next = 0;
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return 0;
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}
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if (index == m->map.max_entries - 1)
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return -ENOENT;
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*next = index + 1;
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return 0;
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}
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struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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struct xdp_sock *xs;
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if (key >= map->max_entries)
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return NULL;
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xs = READ_ONCE(m->xsk_map[key]);
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return xs;
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}
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int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
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struct xdp_sock *xs)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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struct list_head *flush_list = this_cpu_ptr(m->flush_list);
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int err;
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err = xsk_rcv(xs, xdp);
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if (err)
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return err;
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if (!xs->flush_node.prev)
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list_add(&xs->flush_node, flush_list);
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return 0;
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}
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void __xsk_map_flush(struct bpf_map *map)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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struct list_head *flush_list = this_cpu_ptr(m->flush_list);
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struct xdp_sock *xs, *tmp;
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list_for_each_entry_safe(xs, tmp, flush_list, flush_node) {
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xsk_flush(xs);
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__list_del_clearprev(&xs->flush_node);
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}
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}
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static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
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{
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WARN_ON_ONCE(!rcu_read_lock_held());
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return __xsk_map_lookup_elem(map, *(u32 *)key);
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}
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static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
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u64 map_flags)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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struct xdp_sock *xs, *old_xs, **map_entry;
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u32 i = *(u32 *)key, fd = *(u32 *)value;
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struct xsk_map_node *node;
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struct socket *sock;
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int err;
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if (unlikely(map_flags > BPF_EXIST))
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return -EINVAL;
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if (unlikely(i >= m->map.max_entries))
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return -E2BIG;
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sock = sockfd_lookup(fd, &err);
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if (!sock)
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return err;
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if (sock->sk->sk_family != PF_XDP) {
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sockfd_put(sock);
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return -EOPNOTSUPP;
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}
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xs = (struct xdp_sock *)sock->sk;
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if (!xsk_is_setup_for_bpf_map(xs)) {
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sockfd_put(sock);
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return -EOPNOTSUPP;
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}
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map_entry = &m->xsk_map[i];
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node = xsk_map_node_alloc(m, map_entry);
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if (IS_ERR(node)) {
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sockfd_put(sock);
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return PTR_ERR(node);
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}
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spin_lock_bh(&m->lock);
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old_xs = READ_ONCE(*map_entry);
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if (old_xs == xs) {
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err = 0;
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goto out;
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} else if (old_xs && map_flags == BPF_NOEXIST) {
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err = -EEXIST;
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goto out;
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} else if (!old_xs && map_flags == BPF_EXIST) {
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err = -ENOENT;
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goto out;
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}
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xsk_map_sock_add(xs, node);
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WRITE_ONCE(*map_entry, xs);
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if (old_xs)
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xsk_map_sock_delete(old_xs, map_entry);
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spin_unlock_bh(&m->lock);
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sockfd_put(sock);
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return 0;
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out:
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spin_unlock_bh(&m->lock);
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sockfd_put(sock);
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xsk_map_node_free(node);
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return err;
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}
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static int xsk_map_delete_elem(struct bpf_map *map, void *key)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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struct xdp_sock *old_xs, **map_entry;
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int k = *(u32 *)key;
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if (k >= map->max_entries)
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return -EINVAL;
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spin_lock_bh(&m->lock);
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map_entry = &m->xsk_map[k];
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old_xs = xchg(map_entry, NULL);
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if (old_xs)
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xsk_map_sock_delete(old_xs, map_entry);
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spin_unlock_bh(&m->lock);
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return 0;
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}
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void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
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struct xdp_sock **map_entry)
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{
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spin_lock_bh(&map->lock);
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if (READ_ONCE(*map_entry) == xs) {
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WRITE_ONCE(*map_entry, NULL);
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xsk_map_sock_delete(xs, map_entry);
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}
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spin_unlock_bh(&map->lock);
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}
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const struct bpf_map_ops xsk_map_ops = {
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.map_alloc = xsk_map_alloc,
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.map_free = xsk_map_free,
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.map_get_next_key = xsk_map_get_next_key,
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.map_lookup_elem = xsk_map_lookup_elem,
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.map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
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.map_update_elem = xsk_map_update_elem,
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.map_delete_elem = xsk_map_delete_elem,
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.map_check_btf = map_check_no_btf,
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};
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