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Message-ID: <nycvar.YSQ.7.76.2003281745280.2671@knanqh.ubzr>
Date: Sat, 28 Mar 2020 17:59:25 -0400 (EDT)
From: Nicolas Pitre <nico@...xnic.net>
To: gregkh@...uxfoundation.org
cc: Chen Wandun <chenwandun@...wei.com>,
Adam Borowski <kilobyte@...band.pl>, jslaby@...e.com,
daniel.vetter@...ll.ch, sam@...nborg.org, b.zolnierkie@...sung.com,
lukas@...ner.de, ghalat@...hat.com, linux-kernel@...r.kernel.org
Subject: [PATCH] vt: don't use kmalloc() for the unicode screen buffer
Even if the actual screen size is bounded in vc_do_resize(), the unicode
buffer is still a little more than twice the size of the glyph buffer
and may exceed MAX_ORDER down the kmalloc() path. This can be triggered
from user space.
Since there is no point having a physically contiguous buffer here,
let's avoid the above issue as well as reducing pressure on high order
allocations by using vmalloc() instead.
Signed-off-by: Nicolas Pitre <nico@...xnic.net>
Cc: <stable@...r.kernel.org>
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 15d2769805..7c10edb648 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -350,7 +350,7 @@ static struct uni_screen *vc_uniscr_alloc(unsigned int cols, unsigned int rows)
/* allocate everything in one go */
memsize = cols * rows * sizeof(char32_t);
memsize += rows * sizeof(char32_t *);
- p = kmalloc(memsize, GFP_KERNEL);
+ p = vmalloc(memsize);
if (!p)
return NULL;
@@ -366,7 +366,7 @@ static struct uni_screen *vc_uniscr_alloc(unsigned int cols, unsigned int rows)
static void vc_uniscr_set(struct vc_data *vc, struct uni_screen *new_uniscr)
{
- kfree(vc->vc_uni_screen);
+ vfree(vc->vc_uni_screen);
vc->vc_uni_screen = new_uniscr;
}
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