| Message ID | 20240110220124.452746-2-john.fastabend@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | tls fixes for SPLICE with more hint | expand |
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>
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index e37b4d2e2acd..31e8a94dfc11 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1052,7 +1052,11 @@ static int tls_sw_sendmsg_locked(struct sock *sk, struct msghdr *msg, if (ret < 0) goto send_end; tls_ctx->pending_open_record_frags = true; - if (full_record || eor || sk_msg_full(msg_pl)) + + if (sk_msg_full(msg_pl)) + full_record = true; + + if (full_record || eor) goto copied; continue; }
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. Reported-and-tested-by: syzbot+f2977222e0e95cec15c8@syzkaller.appspotmail.com Reported-by: Edward Adam Davis <eadavis@qq.com> Fixes: fe1e81d4f73b ("tls/sw: Support MSG_SPLICE_PAGES") Signed-off-by: John Fastabend <john.fastabend@gmail.com> --- net/tls/tls_sw.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)