stable inclusion
from stable-v5.10.130
commit cecb806c766c78e1be62b6b7b1483ef59bbaeabe
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5IQ4M
CVE: CVE-2021-33655

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cecb806c766c78e1be62b6b7b1483ef59bbaeabe

--------------------------------

commit e64242ca upstream.

We need to prevent that users configure a screen size which is smaller than the
currently selected font size. Otherwise rendering chars on the screen will
access memory outside the graphics memory region.

This patch adds a new function fbcon_modechange_possible() which
implements this check and which later may be extended with other checks
if necessary.  The new function is called from the FBIOPUT_VSCREENINFO
ioctl handler in fbmem.c, which will return -EINVAL if userspace asked
for a too small screen size.
Signed-off-by: NHelge Deller <deller@gmx.de>
Reviewed-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>