From: Bryam Vargas af_iucv queues not-yet-received message notifications on iucv->message_q, each holding a raw pointer to the connection's iucv_path. When the peer severs the connection, iucv_sever_path() frees that path with iucv_path_free() but leaves the notifications queued. A later recvmsg() drains message_q via iucv_process_message_q() and hands the stale path to message_receive() -- a use-after-free of the freed iucv_path. Drop the queued notifications when the path is severed; once the path is gone they can no longer be received. This also frees the notifications leaked when a socket is closed with messages still queued. Fixes: f0703c80e515 ("[AF_IUCV]: postpone receival of iucv-packets") Closes: https://sashiko.dev/#/patchset/20260705-b4-disp-fc79c0dc-v1-1-d2cdcb57afa9@proton.me?part=1 Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas --- net/iucv/af_iucv.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c index fed240b453bd..2869a103f7fa 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -337,6 +337,7 @@ static void iucv_sever_path(struct sock *sk, int with_user_data) unsigned char user_data[16]; struct iucv_sock *iucv = iucv_sk(sk); struct iucv_path *path = iucv->path; + struct sock_msg_q *p, *n; /* Whoever resets the path pointer, must sever and free it. */ if (xchg(&iucv->path, NULL)) { @@ -348,6 +349,19 @@ static void iucv_sever_path(struct sock *sk, int with_user_data) } else pr_iucv->path_sever(path, NULL); iucv_path_free(path); + + /* + * Message notifications queued on message_q still reference + * the now freed path; drop them, otherwise a later recvmsg() + * would pass the freed iucv_path to message_receive() via + * iucv_process_message_q(). + */ + spin_lock_bh(&iucv->message_q.lock); + list_for_each_entry_safe(p, n, &iucv->message_q.list, list) { + list_del(&p->list); + kfree(p); + } + spin_unlock_bh(&iucv->message_q.lock); } } --- base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482 change-id: 20260707-b4-disp-783fedbb-39bc1bb9d4e0 Best regards, -- Bryam Vargas