Commit 2717769e authored Mar 28, 2020 by Nicolas Pitre Committed by Greg Kroah-Hartman Apr 23, 2020

vt: don't hardcode the mem allocation upper bound



The code in vc_do_resize() bounds the memory allocation size to avoid
exceeding MAX_ORDER down the kzalloc() call chain and generating a
runtime warning triggerable from user space. However, not only is it
unwise to use a literal value here, but MAX_ORDER may also be
configurable based on CONFIG_FORCE_MAX_ZONEORDER.
Let's use KMALLOC_MAX_SIZE instead.

Note that prior commit bb1107f7 ("mm, slab: make sure that
KMALLOC_MAX_SIZE will fit into MAX_ORDER") the KMALLOC_MAX_SIZE value
could not be relied upon.

Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Cc: <stable@vger.kernel.org> # v4.10+

Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003281702410.2671@knanqh.ubzr


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

parent abf42d2f

drivers/tty/vt/vt.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1207,7 +1207,7 @@ static int vc_do_resize(struct tty_struct tty, struct vc_data vc,
		if (new_cols == vc->vc_cols && new_rows == vc->vc_rows)
		return 0;

		if (new_screen_size > (4 << 20))
		if (new_screen_size > KMALLOC_MAX_SIZE)
		return -EINVAL;
		newscreen = kzalloc(new_screen_size, GFP_USER);
		if (!newscreen)

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