* [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case
@ 2022-02-03 22:55 Eric Dumazet
2022-02-04 14:39 ` Soheil Hassas Yeganeh
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Eric Dumazet @ 2022-02-03 22:55 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, Eric Dumazet, syzbot, Talal Ahmad,
Arjun Roy, Willem de Bruijn, Soheil Hassas Yeganeh
From: Eric Dumazet <edumazet@google.com>
syzbot found that mixing sendpage() and sendmsg(MSG_ZEROCOPY)
calls over the same TCP socket would again trigger the
infamous warning in inet_sock_destruct()
WARN_ON(sk_forward_alloc_get(sk));
While Talal took into account a mix of regular copied data
and MSG_ZEROCOPY one in the same skb, the sendpage() path
has been forgotten.
We want the charging to happen for sendpage(), because
pages could be coming from a pipe. What is missing is the
downgrading of pure zerocopy status to make sure
sk_forward_alloc will stay synced.
Add tcp_downgrade_zcopy_pure() helper so that we can
use it from the two callers.
Fixes: 9b65b17db723 ("net: avoid double accounting for pure zerocopy skbs")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Talal Ahmad <talalahmad@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
---
net/ipv4/tcp.c | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index bdf108f544a45a2aa24bc962fb81dfd0ca1e0682..e1f259da988df7493ce7d71ad8743ec5025e4e7c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -937,6 +937,22 @@ void tcp_remove_empty_skb(struct sock *sk)
}
}
+/* skb changing from pure zc to mixed, must charge zc */
+static int tcp_downgrade_zcopy_pure(struct sock *sk, struct sk_buff *skb)
+{
+ if (unlikely(skb_zcopy_pure(skb))) {
+ u32 extra = skb->truesize -
+ SKB_TRUESIZE(skb_end_offset(skb));
+
+ if (!sk_wmem_schedule(sk, extra))
+ return ENOMEM;
+
+ sk_mem_charge(sk, extra);
+ skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
+ }
+ return 0;
+}
+
static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
struct page *page, int offset, size_t *size)
{
@@ -972,7 +988,7 @@ static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
tcp_mark_push(tp, skb);
goto new_segment;
}
- if (!sk_wmem_schedule(sk, copy))
+ if (tcp_downgrade_zcopy_pure(sk, skb) || !sk_wmem_schedule(sk, copy))
return NULL;
if (can_coalesce) {
@@ -1320,19 +1336,8 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
copy = min_t(int, copy, pfrag->size - pfrag->offset);
- /* skb changing from pure zc to mixed, must charge zc */
- if (unlikely(skb_zcopy_pure(skb))) {
- u32 extra = skb->truesize -
- SKB_TRUESIZE(skb_end_offset(skb));
-
- if (!sk_wmem_schedule(sk, extra))
- goto wait_for_space;
-
- sk_mem_charge(sk, extra);
- skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
- }
-
- if (!sk_wmem_schedule(sk, copy))
+ if (tcp_downgrade_zcopy_pure(sk, skb) ||
+ !sk_wmem_schedule(sk, copy))
goto wait_for_space;
err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
--
2.35.0.263.gb82422642f-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case
2022-02-03 22:55 [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case Eric Dumazet
@ 2022-02-04 14:39 ` Soheil Hassas Yeganeh
2022-02-05 4:06 ` Jakub Kicinski
2022-02-05 4:30 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 5+ messages in thread
From: Soheil Hassas Yeganeh @ 2022-02-04 14:39 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, Jakub Kicinski, netdev, Eric Dumazet, syzbot,
Talal Ahmad, Arjun Roy, Willem de Bruijn
On Thu, Feb 3, 2022 at 5:55 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> From: Eric Dumazet <edumazet@google.com>
>
> syzbot found that mixing sendpage() and sendmsg(MSG_ZEROCOPY)
> calls over the same TCP socket would again trigger the
> infamous warning in inet_sock_destruct()
>
> WARN_ON(sk_forward_alloc_get(sk));
>
> While Talal took into account a mix of regular copied data
> and MSG_ZEROCOPY one in the same skb, the sendpage() path
> has been forgotten.
>
> We want the charging to happen for sendpage(), because
> pages could be coming from a pipe. What is missing is the
> downgrading of pure zerocopy status to make sure
> sk_forward_alloc will stay synced.
>
> Add tcp_downgrade_zcopy_pure() helper so that we can
> use it from the two callers.
>
> Fixes: 9b65b17db723 ("net: avoid double accounting for pure zerocopy skbs")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Cc: Talal Ahmad <talalahmad@google.com>
> Cc: Arjun Roy <arjunroy@google.com>
> Cc: Willem de Bruijn <willemb@google.com>
> Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Nice catch!
> ---
> net/ipv4/tcp.c | 33 +++++++++++++++++++--------------
> 1 file changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index bdf108f544a45a2aa24bc962fb81dfd0ca1e0682..e1f259da988df7493ce7d71ad8743ec5025e4e7c 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -937,6 +937,22 @@ void tcp_remove_empty_skb(struct sock *sk)
> }
> }
>
> +/* skb changing from pure zc to mixed, must charge zc */
> +static int tcp_downgrade_zcopy_pure(struct sock *sk, struct sk_buff *skb)
> +{
> + if (unlikely(skb_zcopy_pure(skb))) {
> + u32 extra = skb->truesize -
> + SKB_TRUESIZE(skb_end_offset(skb));
> +
> + if (!sk_wmem_schedule(sk, extra))
> + return ENOMEM;
> +
> + sk_mem_charge(sk, extra);
> + skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
> + }
> + return 0;
> +}
> +
> static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
> struct page *page, int offset, size_t *size)
> {
> @@ -972,7 +988,7 @@ static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
> tcp_mark_push(tp, skb);
> goto new_segment;
> }
> - if (!sk_wmem_schedule(sk, copy))
> + if (tcp_downgrade_zcopy_pure(sk, skb) || !sk_wmem_schedule(sk, copy))
> return NULL;
>
> if (can_coalesce) {
> @@ -1320,19 +1336,8 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
>
> copy = min_t(int, copy, pfrag->size - pfrag->offset);
>
> - /* skb changing from pure zc to mixed, must charge zc */
> - if (unlikely(skb_zcopy_pure(skb))) {
> - u32 extra = skb->truesize -
> - SKB_TRUESIZE(skb_end_offset(skb));
> -
> - if (!sk_wmem_schedule(sk, extra))
> - goto wait_for_space;
> -
> - sk_mem_charge(sk, extra);
> - skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
> - }
> -
> - if (!sk_wmem_schedule(sk, copy))
> + if (tcp_downgrade_zcopy_pure(sk, skb) ||
> + !sk_wmem_schedule(sk, copy))
> goto wait_for_space;
>
> err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
> --
> 2.35.0.263.gb82422642f-goog
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case
2022-02-03 22:55 [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case Eric Dumazet
2022-02-04 14:39 ` Soheil Hassas Yeganeh
@ 2022-02-05 4:06 ` Jakub Kicinski
2022-02-05 4:20 ` Eric Dumazet
2022-02-05 4:30 ` patchwork-bot+netdevbpf
2 siblings, 1 reply; 5+ messages in thread
From: Jakub Kicinski @ 2022-02-05 4:06 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, netdev, Eric Dumazet, syzbot, Talal Ahmad,
Arjun Roy, Willem de Bruijn, Soheil Hassas Yeganeh
On Thu, 3 Feb 2022 14:55:47 -0800 Eric Dumazet wrote:
> + if (!sk_wmem_schedule(sk, extra))
> + return ENOMEM;
Let me make this negative when applying, looks like an inconsequential
typo with current callers.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case
2022-02-05 4:06 ` Jakub Kicinski
@ 2022-02-05 4:20 ` Eric Dumazet
0 siblings, 0 replies; 5+ messages in thread
From: Eric Dumazet @ 2022-02-05 4:20 UTC (permalink / raw)
To: Jakub Kicinski
Cc: Eric Dumazet, David S . Miller, netdev, syzbot, Talal Ahmad,
Arjun Roy, Willem de Bruijn, Soheil Hassas Yeganeh
On Fri, Feb 4, 2022 at 8:06 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Thu, 3 Feb 2022 14:55:47 -0800 Eric Dumazet wrote:
> > + if (!sk_wmem_schedule(sk, extra))
> > + return ENOMEM;
>
> Let me make this negative when applying, looks like an inconsequential
> typo with current callers.
Agreed, at first I was returning 0/1, and changed the 1 to ENOMEM at
the last moment.
Thanks !
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case
2022-02-03 22:55 [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case Eric Dumazet
2022-02-04 14:39 ` Soheil Hassas Yeganeh
2022-02-05 4:06 ` Jakub Kicinski
@ 2022-02-05 4:30 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 5+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-02-05 4:30 UTC (permalink / raw)
To: Eric Dumazet
Cc: davem, kuba, netdev, edumazet, syzkaller, talalahmad, arjunroy,
willemb, soheil
Hello:
This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:
On Thu, 3 Feb 2022 14:55:47 -0800 you wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> syzbot found that mixing sendpage() and sendmsg(MSG_ZEROCOPY)
> calls over the same TCP socket would again trigger the
> infamous warning in inet_sock_destruct()
>
> WARN_ON(sk_forward_alloc_get(sk));
>
> [...]
Here is the summary with links:
- [net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case
https://git.kernel.org/netdev/net/c/f8d9d938514f
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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2022-02-03 22:55 [PATCH net] tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case Eric Dumazet
2022-02-04 14:39 ` Soheil Hassas Yeganeh
2022-02-05 4:06 ` Jakub Kicinski
2022-02-05 4:20 ` Eric Dumazet
2022-02-05 4:30 ` patchwork-bot+netdevbpf
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