From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, aszlig , Milan Broz , Daniel Zatovic , Willy Tarreau Subject: [PATCH 4.4 80/86] tty: wipe buffer if not echoing data Date: Thu, 29 Nov 2018 15:12:45 +0100 Message-Id: <20181129140116.199938408@linuxfoundation.org> In-Reply-To: <20181129140109.832117862@linuxfoundation.org> References: <20181129140109.832117862@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Kroah-Hartman commit b97b3d9fb57860a60592859e332de7759fd54c2e upstream. If we are not echoing the data to userspace or the console is in icanon mode, then perhaps it is a "secret" so we should wipe it once we are done with it. This mirrors the logic that the audit code has. Reported-by: aszlig Tested-by: Milan Broz Tested-by: Daniel Zatovic Tested-by: aszlig Cc: Willy Tarreau Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -165,15 +165,29 @@ static inline int tty_put_user(struct tt return put_user(x, ptr); } +/* If we are not echoing the data, perhaps this is a secret so erase it */ +static inline void zero_buffer(struct tty_struct *tty, u8 *buffer, int size) +{ + bool icanon = !!L_ICANON(tty); + bool no_echo = !L_ECHO(tty); + + if (icanon && no_echo) + memset(buffer, 0x00, size); +} + static inline int tty_copy_to_user(struct tty_struct *tty, void __user *to, - const void *from, + void *from, unsigned long n) { struct n_tty_data *ldata = tty->disc_data; + int retval; tty_audit_add_data(tty, from, n, ldata->icanon); - return copy_to_user(to, from, n); + retval = copy_to_user(to, from, n); + if (!retval) + zero_buffer(tty, from, n); + return retval; } /** @@ -2005,6 +2019,7 @@ static int copy_from_read_buf(struct tty is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty); tty_audit_add_data(tty, read_buf_addr(ldata, tail), n, ldata->icanon); + zero_buffer(tty, read_buf_addr(ldata, tail), n); smp_store_release(&ldata->read_tail, ldata->read_tail + n); /* Turn single EOF into zero-length read */ if (L_EXTPROC(tty) && ldata->icanon && is_eof &&