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authorHelge Deller <deller@gmx.de>2022-06-25 13:00:34 +0200
committerHelge Deller <deller@gmx.de>2022-07-07 10:50:46 +0200
commite64242caef18b4a5840b0e7a9bff37abd4f4f933 (patch)
treebe18c49db4dbefbfa6afe060abe7fd645c6b9e3a /drivers/video/fbdev/core/fbmem.c
parentfbcon: Disallow setting font bigger than screen size (diff)
downloadlinux-dev-e64242caef18b4a5840b0e7a9bff37abd4f4f933.tar.xz
linux-dev-e64242caef18b4a5840b0e7a9bff37abd4f4f933.zip
fbcon: Prevent that screen size is smaller than font size
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: Helge Deller <deller@gmx.de> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: stable@vger.kernel.org # v5.4+
Diffstat (limited to '')
-rw-r--r--drivers/video/fbdev/core/fbmem.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index ee63b5b47290..7dc6848a96bb 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1107,7 +1107,9 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
return -EFAULT;
console_lock();
lock_fb_info(info);
- ret = fb_set_var(info, &var);
+ ret = fbcon_modechange_possible(info, &var);
+ if (!ret)
+ ret = fb_set_var(info, &var);
if (!ret)
fbcon_update_vcs(info, var.activate & FB_ACTIVATE_ALL);
unlock_fb_info(info);