* [PATCH net] af_packet: do not use READ_ONCE() in packet_bind()
@ 2023-05-26 15:43 Eric Dumazet
2023-05-26 16:09 ` Willem de Bruijn
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Eric Dumazet @ 2023-05-26 15:43 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski, Paolo Abeni
Cc: netdev, eric.dumazet, Eric Dumazet, Kuniyuki Iwashima, Willem de Bruijn
A recent patch added READ_ONCE() in packet_bind() and packet_bind_spkt()
This is better handled by reading pkt_sk(sk)->num later
in packet_do_bind() while appropriate lock is held.
READ_ONCE() in writers are often an evidence of something being wrong.
Fixes: 822b5a1c17df ("af_packet: Fix data-races of pkt_sk(sk)->num.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Willem de Bruijn <willemb@google.com>
---
net/packet/af_packet.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index a1f9a0e9f3c8a72e5a95f96473b7b6c63f893935..a2dbeb264f260e5b8923ece9aac99fe19ddfeb62 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3201,6 +3201,9 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
lock_sock(sk);
spin_lock(&po->bind_lock);
+ if (!proto)
+ proto = po->num;
+
rcu_read_lock();
if (po->fanout) {
@@ -3299,7 +3302,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data_min));
name[sizeof(uaddr->sa_data_min)] = 0;
- return packet_do_bind(sk, name, 0, READ_ONCE(pkt_sk(sk)->num));
+ return packet_do_bind(sk, name, 0, 0);
}
static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
@@ -3316,8 +3319,7 @@ static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len
if (sll->sll_family != AF_PACKET)
return -EINVAL;
- return packet_do_bind(sk, NULL, sll->sll_ifindex,
- sll->sll_protocol ? : READ_ONCE(pkt_sk(sk)->num));
+ return packet_do_bind(sk, NULL, sll->sll_ifindex, sll->sll_protocol);
}
static struct proto packet_proto = {
--
2.41.0.rc0.172.g3f132b7071-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH net] af_packet: do not use READ_ONCE() in packet_bind()
2023-05-26 15:43 [PATCH net] af_packet: do not use READ_ONCE() in packet_bind() Eric Dumazet
@ 2023-05-26 16:09 ` Willem de Bruijn
2023-05-26 16:14 ` Jiri Pirko
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Willem de Bruijn @ 2023-05-26 16:09 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, Jakub Kicinski, Paolo Abeni, netdev,
eric.dumazet, Kuniyuki Iwashima, Willem de Bruijn
On Fri, May 26, 2023 at 11:43 AM Eric Dumazet <edumazet@google.com> wrote:
>
> A recent patch added READ_ONCE() in packet_bind() and packet_bind_spkt()
>
> This is better handled by reading pkt_sk(sk)->num later
> in packet_do_bind() while appropriate lock is held.
>
> READ_ONCE() in writers are often an evidence of something being wrong.
>
> Fixes: 822b5a1c17df ("af_packet: Fix data-races of pkt_sk(sk)->num.")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
> Cc: Willem de Bruijn <willemb@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Thanks for catching this Eric.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net] af_packet: do not use READ_ONCE() in packet_bind()
2023-05-26 15:43 [PATCH net] af_packet: do not use READ_ONCE() in packet_bind() Eric Dumazet
2023-05-26 16:09 ` Willem de Bruijn
@ 2023-05-26 16:14 ` Jiri Pirko
2023-05-26 16:23 ` Kuniyuki Iwashima
2023-05-30 5:20 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Jiri Pirko @ 2023-05-26 16:14 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, Jakub Kicinski, Paolo Abeni, netdev,
eric.dumazet, Kuniyuki Iwashima, Willem de Bruijn
Fri, May 26, 2023 at 05:43:42PM CEST, edumazet@google.com wrote:
>A recent patch added READ_ONCE() in packet_bind() and packet_bind_spkt()
>
>This is better handled by reading pkt_sk(sk)->num later
>in packet_do_bind() while appropriate lock is held.
Nit: easier to understand the desctiption if you use imperative mood,
telling the codebase what to do.
>
>READ_ONCE() in writers are often an evidence of something being wrong.
>
>Fixes: 822b5a1c17df ("af_packet: Fix data-races of pkt_sk(sk)->num.")
>Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH net] af_packet: do not use READ_ONCE() in packet_bind()
2023-05-26 15:43 [PATCH net] af_packet: do not use READ_ONCE() in packet_bind() Eric Dumazet
2023-05-26 16:09 ` Willem de Bruijn
2023-05-26 16:14 ` Jiri Pirko
@ 2023-05-26 16:23 ` Kuniyuki Iwashima
2023-05-30 5:20 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Kuniyuki Iwashima @ 2023-05-26 16:23 UTC (permalink / raw)
To: edumazet; +Cc: davem, eric.dumazet, kuba, kuniyu, netdev, pabeni, willemb
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 26 May 2023 15:43:42 +0000
> A recent patch added READ_ONCE() in packet_bind() and packet_bind_spkt()
>
> This is better handled by reading pkt_sk(sk)->num later
> in packet_do_bind() while appropriate lock is held.
>
> READ_ONCE() in writers are often an evidence of something being wrong.
>
> Fixes: 822b5a1c17df ("af_packet: Fix data-races of pkt_sk(sk)->num.")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
> Cc: Willem de Bruijn <willemb@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Thanks!
> ---
> net/packet/af_packet.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index a1f9a0e9f3c8a72e5a95f96473b7b6c63f893935..a2dbeb264f260e5b8923ece9aac99fe19ddfeb62 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -3201,6 +3201,9 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
>
> lock_sock(sk);
> spin_lock(&po->bind_lock);
> + if (!proto)
> + proto = po->num;
> +
> rcu_read_lock();
>
> if (po->fanout) {
> @@ -3299,7 +3302,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
> memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data_min));
> name[sizeof(uaddr->sa_data_min)] = 0;
>
> - return packet_do_bind(sk, name, 0, READ_ONCE(pkt_sk(sk)->num));
> + return packet_do_bind(sk, name, 0, 0);
> }
>
> static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
> @@ -3316,8 +3319,7 @@ static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len
> if (sll->sll_family != AF_PACKET)
> return -EINVAL;
>
> - return packet_do_bind(sk, NULL, sll->sll_ifindex,
> - sll->sll_protocol ? : READ_ONCE(pkt_sk(sk)->num));
> + return packet_do_bind(sk, NULL, sll->sll_ifindex, sll->sll_protocol);
> }
>
> static struct proto packet_proto = {
> --
> 2.41.0.rc0.172.g3f132b7071-goog
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net] af_packet: do not use READ_ONCE() in packet_bind()
2023-05-26 15:43 [PATCH net] af_packet: do not use READ_ONCE() in packet_bind() Eric Dumazet
` (2 preceding siblings ...)
2023-05-26 16:23 ` Kuniyuki Iwashima
@ 2023-05-30 5:20 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: patchwork-bot+netdevbpf @ 2023-05-30 5:20 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, kuba, pabeni, netdev, eric.dumazet, kuniyu, willemb
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Fri, 26 May 2023 15:43:42 +0000 you wrote:
> A recent patch added READ_ONCE() in packet_bind() and packet_bind_spkt()
>
> This is better handled by reading pkt_sk(sk)->num later
> in packet_do_bind() while appropriate lock is held.
>
> READ_ONCE() in writers are often an evidence of something being wrong.
>
> [...]
Here is the summary with links:
- [net] af_packet: do not use READ_ONCE() in packet_bind()
https://git.kernel.org/netdev/net/c/6ffc57ea0042
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] 5+ messages in thread
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2023-05-26 15:43 [PATCH net] af_packet: do not use READ_ONCE() in packet_bind() Eric Dumazet
2023-05-26 16:09 ` Willem de Bruijn
2023-05-26 16:14 ` Jiri Pirko
2023-05-26 16:23 ` Kuniyuki Iwashima
2023-05-30 5:20 ` patchwork-bot+netdevbpf
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