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net: use skb_to_full_sk() in skb_update_prio()

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Andrei Vagin reported a KASAN: slab-out-of-bounds error in
skb_update_prio()

Since SYNACK might be attached to a request socket, we need to
get back to the listener socket.
Since this listener is manipulated without locks, add const
qualifiers to sock_cgroup_prioidx() so that the const can also
be used in skb_update_prio()

Also add the const qualifier to sock_cgroup_classid() for consistency.

Fixes: ca6fb06518 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2018-03-14 09:04:16 -07:00 committed by David S. Miller
parent f89782c2d1
commit 4dcb31d464
2 changed files with 17 additions and 9 deletions
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4
include/linux/cgroup-defs.h
View file

@ -755,13 +755,13 @@ struct sock_cgroup_data {
* updaters and return part of the previous pointer as the prioidx or
* classid. Such races are short-lived and the result isn't critical.
*/
static inline u16 sock_cgroup_prioidx(struct sock_cgroup_data *skcd)
static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
{
/* fallback to 1 which is always the ID of the root cgroup */
return (skcd->is_data & 1) ? skcd->prioidx : 1;
}
static inline u32 sock_cgroup_classid(struct sock_cgroup_data *skcd)
static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
{
/* fallback to 0 which is the unconfigured default classid */
return (skcd->is_data & 1) ? skcd->classid : 0;

22
net/core/dev.c
View file

@ -3278,15 +3278,23 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
#if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
static void skb_update_prio(struct sk_buff *skb)
{
struct netprio_map *map = rcu_dereference_bh(skb->dev->priomap);
const struct netprio_map *map;
const struct sock *sk;
unsigned int prioidx;
if (!skb->priority && skb->sk && map) {
unsigned int prioidx =
sock_cgroup_prioidx(&skb->sk->sk_cgrp_data);
if (skb->priority)
return;
map = rcu_dereference_bh(skb->dev->priomap);
if (!map)
return;
sk = skb_to_full_sk(skb);
if (!sk)
return;
if (prioidx < map->priomap_len)
skb->priority = map->priomap[prioidx];
}
prioidx = sock_cgroup_prioidx(&sk->sk_cgrp_data);
if (prioidx < map->priomap_len)
skb->priority = map->priomap[prioidx];
}
#else
#define skb_update_prio(skb)