From: Paulo Alcantara <pc@cjr.nz>
Date: Sat, 28 Nov 2020 16:54:02 -0300
Subject: [PATCH] cifs: fix potential use-after-free in cifs_echo_request()
Git-commit: 212253367dc7b49ed3fc194ce71b0992eacaecf2
References: bsc#1139944
Patch-mainline: v5.10-rc6
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) <pc@cjr.nz>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
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);
--
2.29.2