6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long [ Upstream commit 976c19de0f22a857ba0112f39635f8fd7a257568 ] sctp_free_addr_wq() previously removed addr_wq_timer using timer_delete() while holding addr_wq_lock. However, timer_delete() does not guarantee that a currently running timer handler has completed. This allows a race with sctp_addr_wq_timeout_handler(), where the handler may still run after addr_waitq has been freed, acquire addr_wq_lock, and access freed memory, leading to a use-after-free. Fix this by calling timer_shutdown_sync() before taking addr_wq_lock. This guarantees that any in-flight timer handler has finished and prevents the timer from being re-armed during teardown, making subsequent cleanup safe. Fixes: 4db67e808640 ("sctp: Make the address lists per network namespace") Reported-by: Sashiko Signed-off-by: Xin Long Link: https://patch.msgid.link/5dc95f295bdb5c3f60e880dd9aa5112dc5c071cc.1782757874.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sctp/protocol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index c6d74fa517cd8..66ede52383f86 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -693,8 +693,9 @@ static void sctp_free_addr_wq(struct net *net) struct sctp_sockaddr_entry *addrw; struct sctp_sockaddr_entry *temp; + timer_shutdown_sync(&net->sctp.addr_wq_timer); + spin_lock_bh(&net->sctp.addr_wq_lock); - del_timer(&net->sctp.addr_wq_timer); list_for_each_entry_safe(addrw, temp, &net->sctp.addr_waitq, list) { list_del(&addrw->list); kfree(addrw); -- 2.53.0