* [PATCH net] net: use skb_to_full_sk() in skb_update_prio()
@ 2018-03-14 16:04 Eric Dumazet
2018-03-14 16:55 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2018-03-14 16:04 UTC (permalink / raw)
To: David S . Miller; +Cc: netdev, Eric Dumazet, Andrei Vagin, Eric Dumazet
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: ca6fb0651883 ("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>
---
include/linux/cgroup-defs.h | 4 ++--
net/core/dev.c | 22 +++++++++++++++-------
2 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 9f242b876fde2c29b1d3c023a3934ef01d04cfa9..f8e76d01a5ade411c231c926e55e59a71dde6cc5 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -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;
diff --git a/net/core/dev.c b/net/core/dev.c
index 2cedf520cb28f0c5255b95d0cef536ea21758672..12be205357146f0dcd55cc6e6f71dfb65fdeb33b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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)
--
2.16.2.804.g6dcf76e118-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] net: use skb_to_full_sk() in skb_update_prio()
2018-03-14 16:04 [PATCH net] net: use skb_to_full_sk() in skb_update_prio() Eric Dumazet
@ 2018-03-14 16:55 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2018-03-14 16:55 UTC (permalink / raw)
To: edumazet; +Cc: netdev, avagin, eric.dumazet
From: Eric Dumazet <edumazet@google.com>
Date: Wed, 14 Mar 2018 09:04:16 -0700
> 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: ca6fb0651883 ("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>
Applied and queued up for -stable, thanks!
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-03-14 16:04 [PATCH net] net: use skb_to_full_sk() in skb_update_prio() Eric Dumazet
2018-03-14 16:55 ` David Miller
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