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BUG/MEDIUM: quic: Missing TX buffer draining from qc_send_ppkts()

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If the TX buffer (->tx.buf) attached to the connection is not drained, there
are chances that this will be detected by qc_txb_release() which triggers
a BUG_ON_HOT() when this is the case as follows

[00|quic|2|c_conn.c:3477] UDP port unreachable : qc@0x5584f18d6d50 pto_count=0 cwnd=6816 ppif=1046 pif=1046
[00|quic|5|ic_conn.c:749] qc_kill_conn(): entering : qc@0x5584f18d6d50
[00|quic|5|ic_conn.c:752] qc_kill_conn(): leaving : qc@0x5584f18d6d50
[00|quic|5|c_conn.c:3532] qc_send_ppkts(): leaving : qc@0x5584f18d6d50 pto_count=0 cwnd=6816 ppif=1046 pif=1046

FATAL: bug condition "buf && b_data(buf)" matched at src/quic_conn.c:3098

Consume the remaining data in the TX buffer calling b_del().

This bug arrived with this commit:
    a2c62c314 MINOR: quic: Kill the connections on ICMP (port unreachable) packet receipt

Takes also the opportunity of this patch to modify the comments for qc_send_ppkts()
which should have arrived with a2c62c314 commit.

Must be backported to 2.7 where this latter commit is supposed to be backported.
This commit is contained in:
Frdric Lcaille 2023-02-20 09:28:58 +01:00 committed by Willy Tarreau
parent 0d6e5d271f
commit bbf86be996
1 changed files with 8 additions and 3 deletions
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11
src/quic_conn.c
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@ -3112,6 +3112,8 @@ static void qc_txb_release(struct quic_conn *qc)
/* For the moment sending function is responsible to purge the buffer
* entirely. It may change in the future but this requires to be able
* to reuse old data.
* For the momemt we do not care to leave data in the buffer for
* a connection which is supposed to be killed asap.
*/
BUG_ON_HOT(buf && b_data(buf));
@ -3444,9 +3446,11 @@ static int qc_prep_pkts(struct quic_conn *qc, struct buffer *buf,
/* Send datagrams stored in <buf>.
*
* This function always returns 1 for success. Even if sendto() syscall failed,
* buffer is drained and packets are considered as emitted. QUIC loss detection
* mechanism is used as a back door way to retry sending.
* This function returns 1 for success. Even if sendto() syscall failed,
* buffer is drained and packets are considered as emitted and this function returns 1
* There is a unique exception when sendto() fails with ECONNREFUSED as errno,
* this function returns 0.
* QUIC loss detection mechanism is used as a back door way to retry sending.
*/
int qc_send_ppkts(struct buffer *buf, struct ssl_sock_ctx *ctx)
{
@ -3494,6 +3498,7 @@ int qc_send_ppkts(struct buffer *buf, struct ssl_sock_ctx *ctx)
/* Let's kill this connection asap. */
TRACE_PROTO("UDP port unreachable", QUIC_EV_CONN_SPPKTS, qc);
qc_kill_conn(qc);
b_del(buf, buf->data);
goto leave;
}