* [PATCH net 1/2] net/packet: annotate accesses to po->bind
2021-06-16 13:42 [PATCH net 0/2] net/packet: annotate data races Eric Dumazet
@ 2021-06-16 13:42 ` Eric Dumazet
2021-06-16 13:42 ` [PATCH net 2/2] net/packet: annotate accesses to po->ifindex Eric Dumazet
2021-06-16 19:50 ` [PATCH net 0/2] net/packet: annotate data races patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2021-06-16 13:42 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, Eric Dumazet, syzbot
From: Eric Dumazet <edumazet@google.com>
tpacket_snd(), packet_snd(), packet_getname() and packet_seq_show()
can read po->num without holding a lock. This means other threads
can change po->num at the same time.
KCSAN complained about this known fact [1]
Add READ_ONCE()/WRITE_ONCE() to address the issue.
[1] BUG: KCSAN: data-race in packet_do_bind / packet_sendmsg
write to 0xffff888131a0dcc0 of 2 bytes by task 24714 on cpu 0:
packet_do_bind+0x3ab/0x7e0 net/packet/af_packet.c:3181
packet_bind+0xc3/0xd0 net/packet/af_packet.c:3255
__sys_bind+0x200/0x290 net/socket.c:1637
__do_sys_bind net/socket.c:1648 [inline]
__se_sys_bind net/socket.c:1646 [inline]
__x64_sys_bind+0x3d/0x50 net/socket.c:1646
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae
read to 0xffff888131a0dcc0 of 2 bytes by task 24719 on cpu 1:
packet_snd net/packet/af_packet.c:2899 [inline]
packet_sendmsg+0x317/0x3570 net/packet/af_packet.c:3040
sock_sendmsg_nosec net/socket.c:654 [inline]
sock_sendmsg net/socket.c:674 [inline]
____sys_sendmsg+0x360/0x4d0 net/socket.c:2350
___sys_sendmsg net/socket.c:2404 [inline]
__sys_sendmsg+0x1ed/0x270 net/socket.c:2433
__do_sys_sendmsg net/socket.c:2442 [inline]
__se_sys_sendmsg net/socket.c:2440 [inline]
__x64_sys_sendmsg+0x42/0x50 net/socket.c:2440
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae
value changed: 0x0000 -> 0x1200
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24719 Comm: syz-executor.5 Not tainted 5.13.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
net/packet/af_packet.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 74e6e45a8e8435a556ce813c410a1f4146dd05b6..e91a36bdd1abaf18a679b914ae0d722d42c9369b 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2683,7 +2683,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
}
if (likely(saddr == NULL)) {
dev = packet_cached_dev_get(po);
- proto = po->num;
+ proto = READ_ONCE(po->num);
} else {
err = -EINVAL;
if (msg->msg_namelen < sizeof(struct sockaddr_ll))
@@ -2896,7 +2896,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
if (likely(saddr == NULL)) {
dev = packet_cached_dev_get(po);
- proto = po->num;
+ proto = READ_ONCE(po->num);
} else {
err = -EINVAL;
if (msg->msg_namelen < sizeof(struct sockaddr_ll))
@@ -3171,7 +3171,7 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
/* prevents packet_notifier() from calling
* register_prot_hook()
*/
- po->num = 0;
+ WRITE_ONCE(po->num, 0);
__unregister_prot_hook(sk, true);
rcu_read_lock();
dev_curr = po->prot_hook.dev;
@@ -3181,7 +3181,7 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
}
BUG_ON(po->running);
- po->num = proto;
+ WRITE_ONCE(po->num, proto);
po->prot_hook.type = proto;
if (unlikely(unlisted)) {
@@ -3526,7 +3526,7 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
sll->sll_family = AF_PACKET;
sll->sll_ifindex = po->ifindex;
- sll->sll_protocol = po->num;
+ sll->sll_protocol = READ_ONCE(po->num);
sll->sll_pkttype = 0;
rcu_read_lock();
dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex);
@@ -4414,7 +4414,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
was_running = po->running;
num = po->num;
if (was_running) {
- po->num = 0;
+ WRITE_ONCE(po->num, 0);
__unregister_prot_hook(sk, false);
}
spin_unlock(&po->bind_lock);
@@ -4449,7 +4449,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
spin_lock(&po->bind_lock);
if (was_running) {
- po->num = num;
+ WRITE_ONCE(po->num, num);
register_prot_hook(sk);
}
spin_unlock(&po->bind_lock);
@@ -4619,7 +4619,7 @@ static int packet_seq_show(struct seq_file *seq, void *v)
s,
refcount_read(&s->sk_refcnt),
s->sk_type,
- ntohs(po->num),
+ ntohs(READ_ONCE(po->num)),
po->ifindex,
po->running,
atomic_read(&s->sk_rmem_alloc),
--
2.32.0.272.g935e593368-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH net 2/2] net/packet: annotate accesses to po->ifindex
2021-06-16 13:42 [PATCH net 0/2] net/packet: annotate data races Eric Dumazet
2021-06-16 13:42 ` [PATCH net 1/2] net/packet: annotate accesses to po->bind Eric Dumazet
@ 2021-06-16 13:42 ` Eric Dumazet
2021-06-16 19:50 ` [PATCH net 0/2] net/packet: annotate data races patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2021-06-16 13:42 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, Eric Dumazet, syzbot
From: Eric Dumazet <edumazet@google.com>
Like prior patch, we need to annotate lockless accesses to po->ifindex
For instance, packet_getname() is reading po->ifindex (twice) while
another thread is able to change po->ifindex.
KCSAN reported:
BUG: KCSAN: data-race in packet_do_bind / packet_getname
write to 0xffff888143ce3cbc of 4 bytes by task 25573 on cpu 1:
packet_do_bind+0x420/0x7e0 net/packet/af_packet.c:3191
packet_bind+0xc3/0xd0 net/packet/af_packet.c:3255
__sys_bind+0x200/0x290 net/socket.c:1637
__do_sys_bind net/socket.c:1648 [inline]
__se_sys_bind net/socket.c:1646 [inline]
__x64_sys_bind+0x3d/0x50 net/socket.c:1646
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae
read to 0xffff888143ce3cbc of 4 bytes by task 25578 on cpu 0:
packet_getname+0x5b/0x1a0 net/packet/af_packet.c:3525
__sys_getsockname+0x10e/0x1a0 net/socket.c:1887
__do_sys_getsockname net/socket.c:1902 [inline]
__se_sys_getsockname net/socket.c:1899 [inline]
__x64_sys_getsockname+0x3e/0x50 net/socket.c:1899
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae
value changed: 0x00000000 -> 0x00000001
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25578 Comm: syz-executor.5 Not tainted 5.13.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
net/packet/af_packet.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index e91a36bdd1abaf18a679b914ae0d722d42c9369b..330ba68828e7dbabf4d4d6b76e7cb664253c432e 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3187,11 +3187,11 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
if (unlikely(unlisted)) {
dev_put(dev);
po->prot_hook.dev = NULL;
- po->ifindex = -1;
+ WRITE_ONCE(po->ifindex, -1);
packet_cached_dev_reset(po);
} else {
po->prot_hook.dev = dev;
- po->ifindex = dev ? dev->ifindex : 0;
+ WRITE_ONCE(po->ifindex, dev ? dev->ifindex : 0);
packet_cached_dev_assign(po, dev);
}
}
@@ -3505,7 +3505,7 @@ static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
uaddr->sa_family = AF_PACKET;
memset(uaddr->sa_data, 0, sizeof(uaddr->sa_data));
rcu_read_lock();
- dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
+ dev = dev_get_by_index_rcu(sock_net(sk), READ_ONCE(pkt_sk(sk)->ifindex));
if (dev)
strlcpy(uaddr->sa_data, dev->name, sizeof(uaddr->sa_data));
rcu_read_unlock();
@@ -3520,16 +3520,18 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
struct sock *sk = sock->sk;
struct packet_sock *po = pkt_sk(sk);
DECLARE_SOCKADDR(struct sockaddr_ll *, sll, uaddr);
+ int ifindex;
if (peer)
return -EOPNOTSUPP;
+ ifindex = READ_ONCE(po->ifindex);
sll->sll_family = AF_PACKET;
- sll->sll_ifindex = po->ifindex;
+ sll->sll_ifindex = ifindex;
sll->sll_protocol = READ_ONCE(po->num);
sll->sll_pkttype = 0;
rcu_read_lock();
- dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex);
+ dev = dev_get_by_index_rcu(sock_net(sk), ifindex);
if (dev) {
sll->sll_hatype = dev->type;
sll->sll_halen = dev->addr_len;
@@ -4108,7 +4110,7 @@ static int packet_notifier(struct notifier_block *this,
}
if (msg == NETDEV_UNREGISTER) {
packet_cached_dev_reset(po);
- po->ifindex = -1;
+ WRITE_ONCE(po->ifindex, -1);
if (po->prot_hook.dev)
dev_put(po->prot_hook.dev);
po->prot_hook.dev = NULL;
@@ -4620,7 +4622,7 @@ static int packet_seq_show(struct seq_file *seq, void *v)
refcount_read(&s->sk_refcnt),
s->sk_type,
ntohs(READ_ONCE(po->num)),
- po->ifindex,
+ READ_ONCE(po->ifindex),
po->running,
atomic_read(&s->sk_rmem_alloc),
from_kuid_munged(seq_user_ns(seq), sock_i_uid(s)),
--
2.32.0.272.g935e593368-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH net 0/2] net/packet: annotate data races
2021-06-16 13:42 [PATCH net 0/2] net/packet: annotate data races Eric Dumazet
2021-06-16 13:42 ` [PATCH net 1/2] net/packet: annotate accesses to po->bind Eric Dumazet
2021-06-16 13:42 ` [PATCH net 2/2] net/packet: annotate accesses to po->ifindex Eric Dumazet
@ 2021-06-16 19:50 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-06-16 19:50 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, kuba, netdev, edumazet
Hello:
This series was applied to netdev/net.git (refs/heads/master):
On Wed, 16 Jun 2021 06:42:00 -0700 you wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> KCSAN sent two reports about data races in af_packet.
> Nothing serious, but worth fixing.
>
> Eric Dumazet (2):
> net/packet: annotate accesses to po->bind
> net/packet: annotate accesses to po->ifindex
>
> [...]
Here is the summary with links:
- [net,1/2] net/packet: annotate accesses to po->bind
https://git.kernel.org/netdev/net/c/c7d2ef5dd4b0
- [net,2/2] net/packet: annotate accesses to po->ifindex
https://git.kernel.org/netdev/net/c/e032f7c9c7ce
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 4+ messages in thread