This is a note to let you know that I've just added the patch titled
tty: vt: initialize unicode screen buffer
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-vt-initialize-unicode-screen-buffer.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From af77c56aa35325daa2bc2bed5c2ebf169be61b86 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date: Tue, 19 Jul 2022 14:49:39 +0900
Subject: tty: vt: initialize unicode screen buffer
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
commit af77c56aa35325daa2bc2bed5c2ebf169be61b86 upstream.
syzbot reports kernel infoleak at vcs_read() [1], for buffer can be read
immediately after resize operation. Initialize buffer using kzalloc().
----------
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/fb.h>
int main(int argc, char *argv[])
{
struct fb_var_screeninfo var = { };
const int fb_fd = open("/dev/fb0", 3);
ioctl(fb_fd, FBIOGET_VSCREENINFO, &var);
var.yres = 0x21;
ioctl(fb_fd, FBIOPUT_VSCREENINFO, &var);
return read(open("/dev/vcsu", O_RDONLY), &var, sizeof(var)) == -1;
}
----------
Link: https://syzkaller.appspot.com/bug?extid=31a641689d43387f05d3 [1]
Cc: stable <stable@xxxxxxxxxxxxxxx>
Reported-by: syzbot <syzbot+31a641689d43387f05d3@xxxxxxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jiri Slaby <jirislaby@xxxxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/4ef053cf-e796-fb5e-58b7-3ae58242a4ad@xxxxxxxxxxxxxxxxxxx
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
@@ -351,7 +351,7 @@ static struct uni_screen *vc_uniscr_allo
/* allocate everything in one go */
memsize = cols * rows * sizeof(char32_t);
memsize += rows * sizeof(char32_t *);
- p = vmalloc(memsize);
+ p = vzalloc(memsize);
if (!p)
return NULL;
Patches currently in stable-queue which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
queue-5.4/tty-vt-initialize-unicode-screen-buffer.patch
