lkml.org 
[lkml]   [2020]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2] 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@fluxnic.net>
Cc: <stable@vger.kernel.org>

---

Changes since v1:

- Added missing include, found by kbuild test robot.
Strange that my own build doesn't complain.

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 15d2769805..d9eb5661e9 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -81,6 +81,7 @@
#include <linux/errno.h>
#include <linux/kd.h>
#include <linux/slab.h>
+#include <linux/vmalloc.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/console.h>
@@ -350,7 +351,7 @@ 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 +367,7 @@ 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;
}

\
 
 \ /
  Last update: 2020-03-29 04:25    [W:0.089 / U:0.592 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site