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l2tp: fix l2tp_session_register with colliding l2tpv3 IDs

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When handling colliding L2TPv3 session IDs, we use the existing
session IDR entry and link the new session on that using
session->coll_list. However, when using an existing IDR entry, we must
not do the idr_replace step.

Fixes: aa5e17e1f5 ("l2tp: store l2tpv3 sessions in per-net IDR")
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
James Chapman 2024-07-09 17:28:39 +01:00 committed by David S. Miller
parent b6c6796789
commit 2146b7dd35
1 changed files with 10 additions and 8 deletions
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18
net/l2tp/l2tp_core.c
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@ -436,6 +436,7 @@ int l2tp_session_register(struct l2tp_session *session,
struct l2tp_tunnel *tunnel) struct l2tp_tunnel *tunnel)
{ {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
struct l2tp_session *other_session = NULL;
u32 session_key; u32 session_key;
int err; int err;
@ -456,11 +457,10 @@ int l2tp_session_register(struct l2tp_session *session,
* support existing userspace which depends on it. * support existing userspace which depends on it.
*/ */
if (err == -ENOSPC && tunnel->encap == L2TP_ENCAPTYPE_UDP) { if (err == -ENOSPC && tunnel->encap == L2TP_ENCAPTYPE_UDP) {
struct l2tp_session *session2; other_session = idr_find(&pn->l2tp_v3_session_idr,
session_key);
session2 = idr_find(&pn->l2tp_v3_session_idr, err = l2tp_session_collision_add(pn, session,
session_key); other_session);
err = l2tp_session_collision_add(pn, session, session2);
} }
spin_unlock_bh(&pn->l2tp_session_idr_lock); spin_unlock_bh(&pn->l2tp_session_idr_lock);
} else { } else {
@ -484,10 +484,12 @@ int l2tp_session_register(struct l2tp_session *session,
spin_unlock_bh(&tunnel->list_lock); spin_unlock_bh(&tunnel->list_lock);
spin_lock_bh(&pn->l2tp_session_idr_lock); spin_lock_bh(&pn->l2tp_session_idr_lock);
if (tunnel->version == L2TP_HDR_VER_3) if (tunnel->version == L2TP_HDR_VER_3) {
idr_replace(&pn->l2tp_v3_session_idr, session, session_key); if (!other_session)
else idr_replace(&pn->l2tp_v3_session_idr, session, session_key);
} else {
idr_replace(&pn->l2tp_v2_session_idr, session, session_key); idr_replace(&pn->l2tp_v2_session_idr, session, session_key);
}
spin_unlock_bh(&pn->l2tp_session_idr_lock); spin_unlock_bh(&pn->l2tp_session_idr_lock);
trace_register_session(session); trace_register_session(session);