This issue was discovered during a code audit. After cancel_work_sync() is called from espintcp_close(), espintcp_tx_work() can still be scheduled from paths such as the Delayed ACK handler or ksoftirqd. As a result, the espintcp_tx_work() worker may dereference a freed espintcp ctx or sk. The following is a simple race scenario: cpu0 cpu1 espintcp_close() cancel_work_sync(&ctx->work); espintcp_write_space() schedule_work(&ctx->work); To prevent this race condition, cancel_work_sync() is replaced with disable_work_sync(). Fixes: e27cca96cd68 ("xfrm: add espintcp (RFC 8229)") Signed-off-by: Hyunwoo Kim --- Changes in v2: - Shorten the patch subject - Target the net tree - Add the bug discovery background and the race scenario to the commit message - v1: https://lore.kernel.org/all/aZLmvv51f5Iu9G7b@v4bel/ --- net/xfrm/espintcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c index bf744ac9d5a7..8709df716e98 100644 --- a/net/xfrm/espintcp.c +++ b/net/xfrm/espintcp.c @@ -536,7 +536,7 @@ static void espintcp_close(struct sock *sk, long timeout) sk->sk_prot = &tcp_prot; barrier(); - cancel_work_sync(&ctx->work); + disable_work_sync(&ctx->work); strp_done(&ctx->strp); skb_queue_purge(&ctx->out_queue); -- 2.43.0