On 2023-04-11 15:44, Daniel Vetter wrote:
On Tue, Apr 04, 2023 at 09:39:34PM +0200, Daniel Vetter wrote: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. 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>An Ack on this (or a better idea) would be great, so I can stuff it into -fixes.
Acked-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
