From: Eric Biggers ebiggers@google.com
commit 17329563a97df3ba474eca5037c1336e46e14ff8 upstream.
Commit 77654350306a ("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: 77654350306a ("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
--- drivers/tty/tty_io.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -2731,7 +2731,9 @@ static int compat_tty_tiocgserial(struct 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;