This is a note to let you know that I've just added the patch titled
fbmem: Reject FB_ACTIVATE_KD_TEXT from userspace
to the 5.15-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:
fbmem-reject-fb_activate_kd_text-from-userspace.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6fd33a3333c7916689b8f051a185defe4dd515b0 Mon Sep 17 00:00:00 2001
From: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Tue, 4 Apr 2023 21:39:34 +0200
Subject: fbmem: Reject FB_ACTIVATE_KD_TEXT from userspace
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From: Daniel Vetter <daniel.vetter@xxxxxxxx>
commit 6fd33a3333c7916689b8f051a185defe4dd515b0 upstream.
This is an oversight from dc5bdb68b5b3 ("drm/fb-helper: Fix vt
restore") - I failed to realize that nasty userspace could set this.
It's not pretty to mix up kernel-internal and userspace uapi flags
like this, but since the entire fb_var_screeninfo structure is uapi
we'd need to either add a new parameter to the ->fb_set_par callback
and fb_set_par() function, which has a _lot_ of users. Or some other
fairly ugly side-channel int fb_info. Neither is a pretty prospect.
Instead just correct the issue at hand by filtering out this
kernel-internal flag in the ioctl handling code.
Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Acked-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Fixes: dc5bdb68b5b3 ("drm/fb-helper: Fix vt restore")
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: shlomo@xxxxxxxxxxxx
Cc: Michel Dänzer <michel@xxxxxxxxxxx>
Cc: Noralf Trønnes <noralf@xxxxxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # v5.7+
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Nathan Chancellor <natechancellor@xxxxxxxxx>
Cc: Qiujun Huang <hqjagain@xxxxxxxxx>
Cc: Peter Rosin <peda@xxxxxxxxxx>
Cc: linux-fbdev@xxxxxxxxxxxxxxx
Cc: Helge Deller <deller@xxxxxx>
Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Cc: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230404193934.472457-1-daniel.vetter@xxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/video/fbdev/core/fbmem.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1119,6 +1119,8 @@ static long do_fb_ioctl(struct fb_info *
case FBIOPUT_VSCREENINFO:
if (copy_from_user(&var, argp, sizeof(var)))
return -EFAULT;
+ /* only for kernel-internal use */
+ var.activate &= ~FB_ACTIVATE_KD_TEXT;
console_lock();
lock_fb_info(info);
ret = fbcon_modechange_possible(info, &var);
Patches currently in stable-queue which might be from daniel.vetter@xxxxxxxx are
queue-5.15/fbmem-reject-fb_activate_kd_text-from-userspace.patch
