From 212253367dc7b49ed3fc194ce71b0992eacaecf2 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 28 Nov 2020 16:54:02 -0300 Subject: [PATCH] cifs: fix potential use-after-free in cifs_echo_request() This patch fixes a potential use-after-free bug in cifs_echo_request(). For instance, thread 1 -------- cifs_demultiplex_thread() clean_demultiplex_info() kfree(server) thread 2 (workqueue) -------- apic_timer_interrupt() smp_apic_timer_interrupt() irq_exit() __do_softirq() run_timer_softirq() call_timer_fn() cifs_echo_request() <- use-after-free in server ptr Signed-off-by: Paulo Alcantara (SUSE) CC: Stable Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French --- fs/cifs/connect.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index c38156f324dd..28c1459fb0fc 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -876,6 +876,8 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server) list_del_init(&server->tcp_ses_list); spin_unlock(&cifs_tcp_ses_lock); + cancel_delayed_work_sync(&server->echo); + spin_lock(&GlobalMid_Lock); server->tcpStatus = CifsExiting; spin_unlock(&GlobalMid_Lock);