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| author |   Eric Dumazet <edumazet@google.com> | 2019-03-14 20:19:47 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2019-03-15 15:42:11 -0700 |
| commit | 4477138fa0ae4e1b699786ef0600863ea6e6c61c (patch) | |
| tree | 2afb4ee6fa5cb0effd804cd6b406f71fec6b1ed1 /drivers | |
| parent | net: phy: meson-gxl: fix interrupt support (diff) | |
| download | linux-dev-4477138fa0ae4e1b699786ef0600863ea6e6c61c.tar.xz linux-dev-4477138fa0ae4e1b699786ef0600863ea6e6c61c.zip | |
tun: properly test for IFF_UP
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>
Diffstat (limited to 'drivers')
| -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 1d68921723dc..0d343359f647 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1763,9 +1763,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, int skb_xdp = 1; bool frags = tun_napi_frags_enabled(tfile); - if (!(tun->dev->flags & IFF_UP)) - return -EIO; - if (!(tun->flags & IFF_NO_PI)) { if (len < sizeof(pi)) return -EINVAL; @@ -1867,6 +1864,8 @@ 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); if (frags) { @@ -1874,7 +1873,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, mutex_unlock(&tfile->napi_mutex); } - return -EFAULT; + return err; } } @@ -1958,6 +1957,12 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, !tfile->detached) rxhash = __skb_get_hash_symmetric(skb); + rcu_read_lock(); + if (unlikely(!(tun->dev->flags & IFF_UP))) { + err = -EIO; + goto drop; + } + if (frags) { /* Exercise flow dissector code path. */ u32 headlen = eth_get_headlen(skb->data, skb_headlen(skb)); @@ -1965,6 +1970,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, if (unlikely(headlen > skb_headlen(skb))) { this_cpu_inc(tun->pcpu_stats->rx_dropped); napi_free_frags(&tfile->napi); + rcu_read_unlock(); mutex_unlock(&tfile->napi_mutex); WARN_ON(1); return -ENOMEM; @@ -1992,6 +1998,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, } else { netif_rx_ni(skb); } + rcu_read_unlock(); stats = get_cpu_ptr(tun->pcpu_stats); u64_stats_update_begin(&stats->syncp); |