net/packet: convert po->origdev to an atomic flag

[ Upstream commit ee5675ecdf7a4e713ed21d98a70c2871d6ebed01 ]

syzbot/KCAN reported that po->origdev can be read
while another thread is changing its value.

We can avoid this splat by converting this field
to an actual bit.

Following patches will convert remaining 1bit fields.

Fixes: 80feaacb8a64 ("[AF_PACKET]: Add option to return orig_dev to userspace.")
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: Sasha Levin <sashal@kernel.org>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b5487bd..6c572fc 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2185,7 +2185,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
        sll = &PACKET_SKB_CB(skb)->sa.ll;
        sll->sll_hatype = dev->type;
        sll->sll_pkttype = skb->pkt_type;
-       if (unlikely(po->origdev))
+       if (unlikely(packet_sock_flag(po, PACKET_SOCK_ORIGDEV)))
                sll->sll_ifindex = orig_dev->ifindex;
        else
                sll->sll_ifindex = dev->ifindex;
@@ -2460,7 +2460,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
        sll->sll_hatype = dev->type;
        sll->sll_protocol = skb->protocol;
        sll->sll_pkttype = skb->pkt_type;
-       if (unlikely(po->origdev))
+       if (unlikely(packet_sock_flag(po, PACKET_SOCK_ORIGDEV)))
                sll->sll_ifindex = orig_dev->ifindex;
        else
                sll->sll_ifindex = dev->ifindex;
@@ -3913,9 +3913,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval,
                if (copy_from_sockptr(&val, optval, sizeof(val)))
                        return -EFAULT;
 
-               lock_sock(sk);
-               po->origdev = !!val;
-               release_sock(sk);
+               packet_sock_flag_set(po, PACKET_SOCK_ORIGDEV, val);
                return 0;
        }
        case PACKET_VNET_HDR:
@@ -4064,7 +4062,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
                val = po->auxdata;
                break;
        case PACKET_ORIGDEV:
-               val = po->origdev;
+               val = packet_sock_flag(po, PACKET_SOCK_ORIGDEV);
                break;
        case PACKET_VNET_HDR:
                val = po->has_vnet_hdr;

diff --git a/net/packet/diag.c b/net/packet/diag.c
index 07812ae..e1ac9bb 100644 (file)
--- a/net/packet/diag.c
+++ b/net/packet/diag.c
@@ -25,7 +25,7 @@ static int pdiag_put_info(const struct packet_sock *po, struct sk_buff *nlskb)
                pinfo.pdi_flags |= PDI_RUNNING;
        if (po->auxdata)
                pinfo.pdi_flags |= PDI_AUXDATA;
-       if (po->origdev)
+       if (packet_sock_flag(po, PACKET_SOCK_ORIGDEV))
                pinfo.pdi_flags |= PDI_ORIGDEV;
        if (po->has_vnet_hdr)
                pinfo.pdi_flags |= PDI_VNETHDR;

diff --git a/net/packet/internal.h b/net/packet/internal.h
index 48af35b..178cd18 100644 (file)
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -116,9 +116,9 @@ struct packet_sock {
        int                     copy_thresh;
        spinlock_t              bind_lock;
        struct mutex            pg_vec_lock;
+       unsigned long           flags;
        unsigned int            running;        /* bind_lock must be held */
        unsigned int            auxdata:1,      /* writer must hold sock lock */
-                               origdev:1,
                                has_vnet_hdr:1,
                                tp_loss:1,
                                tp_tx_has_off:1;
@@ -144,4 +144,24 @@ static inline struct packet_sock *pkt_sk(struct sock *sk)
        return (struct packet_sock *)sk;
 }
 
+enum packet_sock_flags {
+       PACKET_SOCK_ORIGDEV,
+};
+
+static inline void packet_sock_flag_set(struct packet_sock *po,
+                                       enum packet_sock_flags flag,
+                                       bool val)
+{
+       if (val)
+               set_bit(flag, &po->flags);
+       else
+               clear_bit(flag, &po->flags);
+}
+
+static inline bool packet_sock_flag(const struct packet_sock *po,
+                                   enum packet_sock_flags flag)
+{
+       return test_bit(flag, &po->flags);
+}
+
 #endif