4.4-stable review patch. If anyone has any objections, please let me know.
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From: Greg Kroah-Hartman greg@kroah.com
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 aszlig@nix.build Tested-by: Milan Broz gmazyland@gmail.com Tested-by: Daniel Zatovic daniel.zatovic@gmail.com Tested-by: aszlig aszlig@nix.build Cc: Willy Tarreau w@1wt.eu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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 &&