Commit 17329563 authored Feb 24, 2020 by Eric Biggers Committed by Greg Kroah-Hartman Mar 18, 2020

tty: fix compat TIOCGSERIAL leaking uninitialized memory



Commit 77654350 ("take compat TIOC[SG]SERIAL treatment into
tty_compat_ioctl()") changed the compat version of TIOCGSERIAL to start
copying a whole 'serial_struct32' to userspace rather than individual
fields, but failed to initialize all padding and fields -- namely the
hole after the 'iomem_reg_shift' field, and the 'reserved' field.

Fix this by initializing the struct to zero.

[v2: use sizeof, and convert the adjacent line for consistency.]

Reported-by:  <syzbot+8da9175e28eadcb203ce@syzkaller.appspotmail.com>
Fixes: 77654350 ("take compat TIOC[SG]SERIAL treatment into tty_compat_ioctl()")
Cc: <stable@vger.kernel.org> # v4.20+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200224182044.234553-2-ebiggers@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent ed069827

drivers/tty/tty_io.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -2730,7 +2730,9 @@ static int compat_tty_tiocgserial(struct tty_struct *tty,
		struct serial_struct32 v32;
		struct serial_struct v;
		int err;
		memset(&v, 0, sizeof(struct serial_struct));

		memset(&v, 0, sizeof(v));
		memset(&v32, 0, sizeof(v32));

		if (!tty->ops->set_serial)
		return -ENOTTY;

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