[PATCH net v4 2/2] sctp: re-point retained control chunks on association migration
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From: Jun Yang <hidden>
Date: 2026-10-09 07:43:14
Also in:
linux-sctp
Subsystem:
networking [general], sctp protocol, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Marcelo Ricardo Leitner, Xin Long, Linus Torvalds
Revision v4 of 2 in this series.
Revisions (2)
- v3 [diff vs current]
- v4 current
From: Jun Yang <redacted>
sctp_sock_migrate() transfers DATA chunk ownership but leaves retained
control chunks pointing at the old socket. A later retransmission can
therefore access the socket after it has been freed.
Extend the migration walk to cover retained control chunks and use
sctp_control_set_owner_w() to assign their new owner. Reuse the DATA
ownership check so each chunk is processed once per pass, even when it
is reachable through multiple lists or retained pointers.
Preserve a control chunk's existing authentication key across migration
so its final release can still generate SCTP_AUTH_FREE_KEY when needed.
Fixes: d04adf1b3551 ("sctp: reset owner sk for data chunks on out queues when migrating a sock")
Cc: stable@kernel.org
Reported-by: TencentOS Corvus AI <redacted>
Assisted-by: tencentos-corvus-ai:hy4-preview
Signed-off-by: Jun Yang <redacted>
---
A KASAN reproducer for this issue is available if requested.
v4:
- Restore sctp_process_tx_chunk() to skip duplicate visits.
- Preserve the control chunk's existing shared key.
v3: https://lore.kernel.org/netdev/20260926100359.78731-3-juny24602@gmail.com/ (local)
v2: https://lore.kernel.org/netdev/20260804113705.45754-1-juny24602@gmail.com/ (local)
v1: https://lore.kernel.org/netdev/20260730090537.27629-1-juny24602@gmail.com/ (local)
include/net/sctp/sm.h | 1 +
net/sctp/sm_make_chunk.c | 5 ++--
net/sctp/socket.c | 53 ++++++++++++++++++++++++++++++----------
3 files changed, 44 insertions(+), 15 deletions(-)
diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index 3bfd261a53cc..76605d1ee839 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h@@ -252,6 +252,7 @@ struct sctp_chunk *sctp_make_fwdtsn(const struct sctp_association *asoc, struct sctp_fwdtsn_skip *skiplist); struct sctp_chunk *sctp_make_auth(const struct sctp_association *asoc, __u16 key_id); +void sctp_control_set_owner_w(struct sctp_chunk *chunk); struct sctp_chunk *sctp_make_strreset_req(const struct sctp_association *asoc, __u16 stream_num, __be16 *stream_list, bool out, bool in);
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 84a4c97d0f75..ddc31a5dbad3 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c@@ -94,7 +94,7 @@ static void sctp_control_release_owner(struct sk_buff *skb) } } -static void sctp_control_set_owner_w(struct sctp_chunk *chunk) +void sctp_control_set_owner_w(struct sctp_chunk *chunk) { struct sctp_association *asoc = chunk->asoc; struct sk_buff *skb = chunk->skb;
@@ -107,7 +107,8 @@ static void sctp_control_set_owner_w(struct sctp_chunk *chunk) * For now don't do anything for now. */ if (chunk->auth) { - chunk->shkey = asoc->shkey; + if (!chunk->shkey) + chunk->shkey = asoc->shkey; sctp_auth_shkey_hold(chunk->shkey); } skb->sk = asoc ? asoc->base.sk : NULL;
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 4a08023d52aa..d09b9f139070 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c@@ -155,9 +155,24 @@ static void sctp_clear_owner_w(struct sctp_chunk *chunk) static void sctp_set_owner_w_migrate(struct sctp_chunk *chunk) { - sctp_set_owner_w(chunk); - if (chunk->shkey) - sctp_auth_shkey_release(chunk->shkey); + struct sctp_shared_key *shkey = chunk->shkey; + + if (chunk->msg) + sctp_set_owner_w(chunk); + else + sctp_control_set_owner_w(chunk); + + if (shkey) + sctp_auth_shkey_release(shkey); +} + +static void sctp_process_tx_chunk(struct sctp_association *asoc, + struct sctp_chunk *chunk, bool clear, + void (*cb)(struct sctp_chunk *)) +{ + if ((clear && asoc->base.sk == chunk->skb->sk) || + (!clear && asoc->base.sk != chunk->skb->sk)) + cb(chunk); } #define traverse_and_process() \
@@ -165,17 +180,14 @@ do { \ msg = chunk->msg; \ if (msg == prev_msg) \ continue; \ - list_for_each_entry(c, &msg->chunks, frag_list) { \ - if ((clear && asoc->base.sk == c->skb->sk) || \ - (!clear && asoc->base.sk != c->skb->sk)) \ - cb(c); \ - } \ + list_for_each_entry(c, &msg->chunks, frag_list) \ + sctp_process_tx_chunk(asoc, c, clear, cb); \ prev_msg = msg; \ } while (0) -static void sctp_for_each_tx_datachunk(struct sctp_association *asoc, - bool clear, - void (*cb)(struct sctp_chunk *)) +static void sctp_for_each_tx_chunk(struct sctp_association *asoc, + bool clear, + void (*cb)(struct sctp_chunk *)) { struct sctp_datamsg *msg, *prev_msg = NULL;
@@ -198,6 +210,21 @@ static void sctp_for_each_tx_datachunk(struct sctp_association *asoc, list_for_each_entry(chunk, &q->out_chunk_list, list) traverse_and_process(); + + list_for_each_entry(chunk, &q->control_chunk_list, list) + sctp_process_tx_chunk(asoc, chunk, clear, cb); + + list_for_each_entry(chunk, &asoc->asconf_ack_list, transmitted_list) + sctp_process_tx_chunk(asoc, chunk, clear, cb); + + list_for_each_entry(chunk, &asoc->addip_chunk_list, list) + sctp_process_tx_chunk(asoc, chunk, clear, cb); + + if (asoc->strreset_chunk) + sctp_process_tx_chunk(asoc, asoc->strreset_chunk, clear, cb); + + if (asoc->addip_last_asconf) + sctp_process_tx_chunk(asoc, asoc->addip_last_asconf, clear, cb); } static void sctp_for_each_rx_skb(struct sctp_association *asoc, struct sock *sk,
@@ -9640,9 +9667,9 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, * paths won't try to lock it and then oldsk. */ lock_sock_nested(newsk, SINGLE_DEPTH_NESTING); - sctp_for_each_tx_datachunk(assoc, true, sctp_clear_owner_w); + sctp_for_each_tx_chunk(assoc, true, sctp_clear_owner_w); sctp_assoc_migrate(assoc, newsk); - sctp_for_each_tx_datachunk(assoc, false, sctp_set_owner_w_migrate); + sctp_for_each_tx_chunk(assoc, false, sctp_set_owner_w_migrate); /* If the association on the newsk is already closed before accept() * is called, set RCV_SHUTDOWN flag.