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authorEric Dumazet <edumazet@google.com>2019-03-14 20:19:47 -0700
committerDavid S. Miller <davem@davemloft.net>2019-03-15 15:42:11 -0700
commit4477138fa0ae4e1b699786ef0600863ea6e6c61c (patch)
tree2afb4ee6fa5cb0effd804cd6b406f71fec6b1ed1 /drivers/net
parentnet: phy: meson-gxl: fix interrupt support (diff)
downloadlinux-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/net')
-rw-r--r--drivers/net/tun.c15
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);