diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-10-19 02:14:52 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-21 03:51:34 +0300 |
| commit | 509c7a1ecc8601f94ffba8a00889fefb239c00c6 (patch) | |
| tree | f9dcb3f8a8782f6c6bbc6231e9eea2382146d36b /net | |
| parent | c92e8c02fe664155ac4234516e32544bec0f113d (diff) | |
| download | linux-509c7a1ecc8601f94ffba8a00889fefb239c00c6.tar.xz | |
packet: avoid panic in packet_getsockopt()
syzkaller got crashes in packet_getsockopt() processing
PACKET_ROLLOVER_STATS command while another thread was managing
to change po->rollover
Using RCU will fix this bug. We might later add proper RCU annotations
for sparse sake.
In v2: I replaced kfree(rollover) in fanout_add() to kfree_rcu()
variant, as spotted by John.
Fixes: a9b6391814d5 ("packet: rollover statistics")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: John Sperbeck <jsperbeck@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/packet/af_packet.c | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index bec01a3daf5b..2986941164b1 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1769,7 +1769,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) out: if (err && rollover) { - kfree(rollover); + kfree_rcu(rollover, rcu); po->rollover = NULL; } mutex_unlock(&fanout_mutex); @@ -1796,8 +1796,10 @@ static struct packet_fanout *fanout_release(struct sock *sk) else f = NULL; - if (po->rollover) + if (po->rollover) { kfree_rcu(po->rollover, rcu); + po->rollover = NULL; + } } mutex_unlock(&fanout_mutex); @@ -3851,6 +3853,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, void *data = &val; union tpacket_stats_u st; struct tpacket_rollover_stats rstats; + struct packet_rollover *rollover; if (level != SOL_PACKET) return -ENOPROTOOPT; @@ -3929,13 +3932,18 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, 0); break; case PACKET_ROLLOVER_STATS: - if (!po->rollover) + rcu_read_lock(); + rollover = rcu_dereference(po->rollover); + if (rollover) { + rstats.tp_all = atomic_long_read(&rollover->num); + rstats.tp_huge = atomic_long_read(&rollover->num_huge); + rstats.tp_failed = atomic_long_read(&rollover->num_failed); + data = &rstats; + lv = sizeof(rstats); + } + rcu_read_unlock(); + if (!rollover) return -EINVAL; - rstats.tp_all = atomic_long_read(&po->rollover->num); - rstats.tp_huge = atomic_long_read(&po->rollover->num_huge); - rstats.tp_failed = atomic_long_read(&po->rollover->num_failed); - data = &rstats; - lv = sizeof(rstats); break; case PACKET_TX_HAS_OFF: val = po->tp_tx_has_off; |