From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paulo Alcantara Subject: Re: [PATCH] CIFS: fix use-after-free of the lease keys Date: Thu, 31 Jan 2019 10:52:29 -0200 Message-ID: <87zhrhat0y.fsf@paulo.ac> References: <20190131124607.2458-1-aaptel@suse.com> Mime-Version: 1.0 Content-Type: text/plain Cc: smfrench@gmail.com, Aurelien Aptel , stable@vger.kernel.org To: Aurelien Aptel , linux-cifs@vger.kernel.org Return-path: In-Reply-To: <20190131124607.2458-1-aaptel@suse.com> Sender: stable-owner@vger.kernel.org List-Id: linux-cifs.vger.kernel.org Aurelien Aptel writes: > 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 Reviewed-by: Paulo Alcantara Thanks! Paulo