iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

packet: avoid panic in packet_getsockopt()

Browse Source 
[ Upstream commit 509c7a1ecc8601f94ffba8a00889fefb239c00c6 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2017-10-18 16:14:52 -07:00 committed by Greg Kroah-Hartman
parent 2ffd261337
commit 57ffb0ecf3
1 changed files with 16 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
net/packet/af_packet.c
View File

@ -1720,7 +1720,7 @@ 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);
@ -1747,8 +1747,10 @@ 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;