[PATCH 5.19 0111/1157] ksmbd: fix use-after-free bug in smb2_tree_disconect

Greg Kroah-Hartman
2022-08-15T22:28:19Z

From: Namjae Jeon <linkinjeon@kernel.org>

commit cf6531d98190fa2cf92a6d8bbc8af0a4740a223c upstream.

smb2_tree_disconnect() freed the struct ksmbd_tree_connect,
but it left the dangling pointer. It can be accessed
again under compound requests.

This bug can lead an oops looking something link:

[ 1685.468014 ] BUG: KASAN: use-after-free in ksmbd_tree_conn_disconnect+0x131/0x160 [ksmbd]
[ 1685.468068 ] Read of size 4 at addr ffff888102172180 by task kworker/1:2/4807
...
[ 1685.468130 ] Call Trace:
[ 1685.468132 ] <TASK>
[ 1685.468135 ] dump_stack_lvl+0x49/0x5f
[ 1685.468141 ] print_report.cold+0x5e/0x5cf
[ 1685.468145 ] ? ksmbd_tree_conn_disconnect+0x131/0x160 [ksmbd]
[ 1685.468157 ] kasan_report+0xaa/0x120
[ 1685.468194 ] ? ksmbd_tree_conn_disconnect+0x131/0x160 [ksmbd]
[ 1685.468206 ] __asan_report_load4_noabort+0x14/0x20
[ 1685.468210 ] ksmbd_tree_conn_disconnect+0x131/0x160 [ksmbd]
[ 1685.468222 ] smb2_tree_disconnect+0x175/0x250 [ksmbd]
[ 1685.468235 ] handle_ksmbd_work+0x30e/0x1020 [ksmbd]
[ 1685.468247 ] process_one_work+0x778/0x11c0
[ 1685.468251 ] ? _raw_spin_lock_irq+0x8e/0xe0
[ 1685.468289 ] worker_thread+0x544/0x1180
[ 1685.468293 ] ? __cpuidle_text_end+0x4/0x4
[ 1685.468297 ] kthread+0x282/0x320
[ 1685.468301 ] ? process_one_work+0x11c0/0x11c0
[ 1685.468305 ] ? kthread_complete_and_exit+0x30/0x30
[ 1685.468309 ] ret_from_fork+0x1f/0x30

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-17816
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ksmbd/smb2pdu.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2043,6 +2043,7 @@ int smb2_tree_disconnect(struct ksmbd_wo

ksmbd_close_tree_conn_fds(work);
ksmbd_tree_conn_disconnect(sess, tcon);
+ work->tcon = NULL;
return 0;
}