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Commit 2b7e9180 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman Committed by Greg Kroah-Hartman
Browse files

tty: wipe buffer if not echoing data 



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: default avataraszlig <aszlig@nix.build>
Tested-by: default avatarMilan Broz <gmazyland@gmail.com>
Tested-by: default avatarDaniel Zatovic <daniel.zatovic@gmail.com>
Tested-by: default avataraszlig <aszlig@nix.build>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d196147e

drivers/tty/n_tty.c

+17 −2
Original line number Diff line number Diff line
@@ -165,15 +165,29 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x, 
	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_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 &&