From: Jakub Kicinski <kuba@kernel.org>
To: John Fastabend <john.fastabend@gmail.com>
Cc: netdev@vger.kernel.org, eadavis@qq.com, bpf@vger.kernel.org,
borisp@nvidia.com
Subject: Re: [PATCH net 1/2] net: tls, fix WARNIING in __sk_msg_free
Date: Thu, 11 Jan 2024 17:05:13 -0800 [thread overview]
Message-ID: <20240111170513.7f8cd768@kernel.org> (raw)
In-Reply-To: <20240110220124.452746-2-john.fastabend@gmail.com>
On Wed, 10 Jan 2024 14:01:23 -0800 John Fastabend wrote:
> A splice with MSG_SPLICE_PAGES will cause tls code to use the
> tls_sw_sendmsg_splice path in the TLS sendmsg code to move the user
> provided pages from the msg into the msg_pl. This will loop over the
> msg until msg_pl is full, checked by sk_msg_full(msg_pl). The user
> can also set the MORE flag to hint stack to delay sending until receiving
> more pages and ideally a full buffer.
>
> If the user adds more pages to the msg than can fit in the msg_pl
> scatterlist (MAX_MSG_FRAGS) we should ignore the MORE flag and send
> the buffer anyways.
>
> What actually happens though is we abort the msg to msg_pl scatterlist
> setup and then because we forget to set 'full record' indicating we
> can no longer consume data without a send we fallthrough to the 'continue'
> path which will check if msg_data_left(msg) has more bytes to send and
> then attempts to fit them in the already full msg_pl. Then next
> iteration of sender doing send will encounter a full msg_pl and throw
> the warning in the syzbot report.
>
> To fix simply check if we have a full_record in splice code path and
> if not send the msg regardless of MORE flag.
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
next prev parent reply other threads:[~2024-01-12 1:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-10 22:01 [PATCH net 0/2] tls fixes for SPLICE with more hint John Fastabend
2024-01-10 22:01 ` [PATCH net 1/2] net: tls, fix WARNIING in __sk_msg_free John Fastabend
2024-01-12 1:05 ` Jakub Kicinski [this message]
2024-01-10 22:01 ` [PATCH net 2/2] net: tls, add test to capture error on large splice John Fastabend
2024-01-12 1:05 ` Jakub Kicinski
2024-01-12 21:52 ` John Fastabend
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