diff options
| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2021-05-15 03:00:37 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-26 11:27:34 +0200 |
| commit | e6c40c7df14497169e00e1e776c4cdb19d7d6bc0 (patch) | |
| tree | 50acdcb594ee3361324e0f917b0b961a646ff64c /drivers/video/console | |
| parent | cf4cdc59a1e401cdc01944488d88068aafda8f8d (diff) | |
tty: vt: always invoke vc->vc_sw->con_resize callback
commit ffb324e6f874121f7dce5bdae5e05d02baae7269 upstream.
syzbot is reporting OOB write at vga16fb_imageblit() [1], for
resize_screen() from ioctl(VT_RESIZE) returns 0 without checking whether
requested rows/columns fit the amount of memory reserved for the graphical
screen if current mode is KD_GRAPHICS.
----------
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/kd.h>
#include <linux/vt.h>
int main(int argc, char *argv[])
{
const int fd = open("/dev/char/4:1", O_RDWR);
struct vt_sizes vt = { 0x4100, 2 };
ioctl(fd, KDSETMODE, KD_GRAPHICS);
ioctl(fd, VT_RESIZE, &vt);
ioctl(fd, KDSETMODE, KD_TEXT);
return 0;
}
----------
Allow framebuffer drivers to return -EINVAL, by moving vc->vc_mode !=
KD_GRAPHICS check from resize_screen() to fbcon_resize().
Link: https://syzkaller.appspot.com/bug?extid=1f29e126cf461c4de3b3 [1]
Reported-by: syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/video/console')
| -rw-r--r-- | drivers/video/console/fbcon.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index 29bb67921639..ceae076dc96b 100644 --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -1986,7 +1986,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width, return -EINVAL; DPRINTK("resize now %ix%i\n", var.xres, var.yres); - if (CON_IS_VISIBLE(vc)) { + if (CON_IS_VISIBLE(vc) && vc->vc_mode == KD_TEXT) { var.activate = FB_ACTIVATE_NOW | FB_ACTIVATE_FORCE; fb_set_var(info, &var); |