This is a note to let you know that I've just added the patch titled
vt: don't use kmalloc() for the unicode screen buffer
to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From 9a98e7a80f95378c9ee0c644705e3b5aa54745f1 Mon Sep 17 00:00:00 2001
From: Nicolas Pitre nico@fluxnic.net Date: Sat, 28 Mar 2020 22:25:11 -0400 Subject: 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 Acked-by: Sam Ravnborg sam@ravnborg.org Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003282214210.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/vt/vt.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 309a39197be0..3272759b1f3c 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; }