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tty: fix compat TIOCGSERIAL leaking uninitialized memory 

Commit 7765435030 ("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: 7765435030 ("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>
alistair/sensors
Eric Biggers 2020-02-24 10:20:43 -08:00 committed by Greg Kroah-Hartman
parent ed069827ca
commit 17329563a9
1 changed files with 3 additions and 1 deletions
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4
drivers/tty/tty_io.c
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@ -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;