From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aurelien Aptel Subject: [PATCH] CIFS: fix use-after-free of the lease keys Date: Thu, 31 Jan 2019 13:46:07 +0100 Message-ID: <20190131124607.2458-1-aaptel@suse.com> Cc: smfrench@gmail.com, Aurelien Aptel , stable@vger.kernel.org To: linux-cifs@vger.kernel.org Return-path: Sender: stable-owner@vger.kernel.org List-Id: linux-cifs.vger.kernel.org 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 --- 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 846e605175bf..54181387a770 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -4435,8 +4435,8 @@ 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, -- 2.16.4