modesetting: Fix front_bo leak at drmmode_xf86crtc_resize on XRandR rotation

Since the introduction of "modesetting: Remove unnecessary fb addition from
drmmode_xf86crtc_resize" the fb_id isn't initialited at

Rotate operation of XRandR uses rotate_bo. So in this case the fb_id
associated to the front_bo is not initialized at drmmode_set_mode_major.
So fd_id remains 0.

As every call to drmmode_xf86crtc_resize allocates a new front_bo we should
destroy unconditionally the old_front_bo if operation success. So we free
the allocated GBM handles.

This avoids crashing xserver with a OOM in the RPI4 1Gb at 4k resolution
after 3 series xrandr rotations from normal to left and vice versa reported at

Signed-off-by: Jose Maria Casanova Crespo <>
Reviewed-by: Keith Packard <>
Closes: xorg/xserver#1024
Fixes: 87745321 "modesetting: Remove unnecessary fb addition from
(cherry picked from commit 73480f17)
3 jobs for fix-front_bo-leak-1.20 in 4 minutes and 59 seconds (queued for 1 second)