From: Eric Dumazet edumazet@google.com
[ 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 --- net/packet/af_packet.c | 10 ++++------ net/packet/diag.c | 2 +- net/packet/internal.h | 22 +++++++++++++++++++++- 3 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 8636e74557ec2..0e88a8dd4530f 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2125,7 +2125,7 @@ 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; @@ -2393,7 +2393,7 @@ 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; @@ -3853,9 +3853,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv if (copy_from_user(&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: @@ -4007,7 +4005,7 @@ 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 07812ae5ca073..e1ac9bb375b31 100644 --- 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 907f4cd2a7188..23649010e9586 100644 --- a/net/packet/internal.h +++ b/net/packet/internal.h @@ -115,9 +115,9 @@ 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; @@ -143,4 +143,24 @@ static 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