diff options
author | Eric Dumazet <edumazet@google.com> | 2019-03-14 20:19:47 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-03 06:25:11 +0200 |
commit | 63a85fb4871a096c3bd5777b9f870b2386f45160 (patch) | |
tree | cbcc7cbfb3adaec2e50591fd0e8644cf7da54d19 /drivers/net/tun.c | |
parent | f8a85be02fb76fcce4ebf623d42cce4ffbefddb9 (diff) |
tun: properly test for IFF_UP
[ Upstream commit 4477138fa0ae4e1b699786ef0600863ea6e6c61c ]
Same reasons than the ones explained in commit 4179cb5a4c92
("vxlan: test dev->flags & IFF_UP before calling netif_rx()")
netif_rx_ni() or napi_gro_frags() must be called under a strict contract.
At device dismantle phase, core networking clears IFF_UP
and flush_all_backlogs() is called after rcu grace period
to make sure no incoming packet might be in a cpu backlog
and still referencing the device.
A similar protocol is used for gro layer.
Most drivers call netif_rx() from their interrupt handler,
and since the interrupts are disabled at device dismantle,
netif_rx() does not have to check dev->flags & IFF_UP
Virtual drivers do not have this guarantee, and must
therefore make the check themselves.
Fixes: 1bd4978a88ac ("tun: honor IFF_UP in tun_get_user()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/net/tun.c')
-rw-r--r-- | drivers/net/tun.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 4227ee33ef19..9d6431d13c98 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1403,9 +1403,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, u32 rxhash; int skb_xdp = 1; - if (!(tun->dev->flags & IFF_UP)) - return -EIO; - if (!(tun->flags & IFF_NO_PI)) { if (len < sizeof(pi)) return -EINVAL; @@ -1493,9 +1490,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, err = skb_copy_datagram_from_iter(skb, 0, from, len); if (err) { + err = -EFAULT; +drop: this_cpu_inc(tun->pcpu_stats->rx_dropped); kfree_skb(skb); - return -EFAULT; + return err; } } @@ -1566,11 +1565,19 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, } rxhash = __skb_get_hash_symmetric(skb); + + rcu_read_lock(); + if (unlikely(!(tun->dev->flags & IFF_UP))) { + err = -EIO; + goto drop; + } + #ifndef CONFIG_4KSTACKS tun_rx_batched(tun, tfile, skb, more); #else netif_rx_ni(skb); #endif + rcu_read_unlock(); stats = get_cpu_ptr(tun->pcpu_stats); u64_stats_update_begin(&stats->syncp); |