From: Nicolas Pitre <nico@xxxxxxxxxxx>
commit 2717769e204e83e65b8819c5e2ef3e5b6639b270 upstream.
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 bb1107f7c605 ("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@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.10+
Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003281702410.2671@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/vt/vt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -880,7 +880,7 @@ static int vc_do_resize(struct tty_struc
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)
