From eb1a097a6687cd8b93d981eff3d7e257c448ff3e Mon Sep 17 00:00:00 2001 From: Frederic Lecaille Date: Mon, 5 Aug 2024 13:40:51 +0200 Subject: [PATCH] BUG/MINOR: quic: Too short datagram during packet building failures (aws-lc only) This issue was reported by Ilya (@Chipitsine) when building haproxy against aws-lc in GH #2663 where handshakeloss and handshakecorruption interop tests could lead haproxy to crash after having built too short datagrams: FATAL: bug condition "first_pkt->type == QUIC_PACKET_TYPE_INITIAL && (first_pkt->flags & (1UL << 0)) && length < 1200" matched at src/quic_tx.c:163 call trace(13): | 0x55f4ee4dcc02 [ba d9 00 00 00 48 8d 35]: main-0x195bf2 | 0x55f4ee4e3112 [83 3d 2f 16 35 00 00 0f]: qc_send+0x11f3/0x1b5d | 0x55f4ee4e9ab4 [85 c0 0f 85 00 f6 ff ff]: quic_conn_io_cb+0xab1/0xf1c | 0x55f4ee6efa82 [48 c7 c0 f8 55 ff ff 64]: run_tasks_from_lists+0x173/0x9c2 | 0x55f4ee6f05d3 [8b 7d a0 29 c7 85 ff 0f]: process_runnable_tasks+0x302/0x6e6 | 0x55f4ee671bb7 [83 3d 86 72 44 00 01 0f]: run_poll_loop+0x6e/0x57b | 0x55f4ee672367 [48 8b 1d 22 d4 1d 00 48]: main-0x48d | 0x55f4ee6755e0 [b8 00 00 00 00 e8 08 61]: main+0x2dec/0x335d This could happen after Handshake packet building failures which follow a successful Initial packet into the same datagram. In this case, the datagram could be emitted with a too short length (<1200 bytes). To fix this, store the datagram only if the first packet is not an Initial packet or if its length is big enough (>=1200 bytes). Must be backported as far as 2.6. --- src/quic_tx.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/quic_tx.c b/src/quic_tx.c index 5f81978abda3f..4126d6423185c 100644 --- a/src/quic_tx.c +++ b/src/quic_tx.c @@ -643,7 +643,11 @@ static int qc_prep_pkts(struct quic_conn *qc, struct buffer *buf, break; case QC_BUILD_PKT_ERR_BUFROOM: - if (first_pkt) + /* If a first packet could be built, do not lose it, + * except if it is an too short Initial. + */ + if (first_pkt && (first_pkt->type != QUIC_PACKET_TYPE_INITIAL || + wrlen >= QUIC_INITIAL_PACKET_MINLEN)) qc_txb_store(buf, wrlen, first_pkt); TRACE_PROTO("could not prepare anymore packet", QUIC_EV_CONN_PHPKTS, qc, qel); break;