From d339adc12a4f885b572c5412e4869af8939db854 Mon Sep 17 00:00:00 2001 From: Aurelien Aptel Date: Thu, 31 Jan 2019 13:46:07 +0100 Subject: [PATCH] CIFS: fix use-after-free of the lease keys The request buffers are freed right before copying the pointers. Use the func args instead which are identical and still valid. Simple reproducer (requires KASAN enabled) on a cifs mount: echo foo > foo ; tail -f foo & rm foo Cc: # 4.20 Fixes: 179e44d49c2f ("smb3: add tracepoint for sending lease break responses to server") Signed-off-by: Aurelien Aptel Signed-off-by: Steve French Reviewed-by: Paulo Alcantara --- fs/cifs/smb2pdu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index ef52d6642431..77b3aaa39b35 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -4441,8 +4441,8 @@ SMB2_lease_break(const unsigned int xid, struct cifs_tcon *tcon, rc = cifs_send_recv(xid, ses, &rqst, &resp_buf_type, flags, &rsp_iov); cifs_small_buf_release(req); - please_key_low = (__u64 *)req->LeaseKey; - please_key_high = (__u64 *)(req->LeaseKey+8); + please_key_low = (__u64 *)lease_key; + please_key_high = (__u64 *)(lease_key+8); if (rc) { cifs_stats_fail_inc(tcon, SMB2_OPLOCK_BREAK_HE); trace_smb3_lease_err(le32_to_cpu(lease_state), tcon->tid,