Den 09.05.2022 10.15, skrev Thomas Zimmermann:
Some DRM helpers assume that all potential color planes of a framebuffer are available; even if the color format didn't specify them. Non-existing planes are silently ignored. This behavior is inconsistent with other helpers and apparently leads to subtle bugs with uninitialized GEM buffer mappings. [1]
Change all affected code to look at the framebuffer format's number of color planes and only process these planes. The update has been discussed in [2] before.
Tested with GEM SHMEM helpers on simpledrm.
Tested with drm/gud, now there's only one UBSAN warning:
Tested-by: Noralf Trønnes noralf@tronnes.org
I was hoping to get some time to give a review, but it doesn't look like I'm able to do that.
Noralf.
[1] https://lore.kernel.org/dri-devel/20210730183511.20080-1-tzimmermann@suse.de... [2] https://lore.kernel.org/dri-devel/877dc0d9-c6c6-022c-20d8-14b33e863934@suse....
Thomas Zimmermann (4): drm/gem: Share code between drm_gem_fb_{begin,end}_cpu_access() drm/gem: Ignore color planes that are unused by framebuffer format drm/gem-vram: Ignore planes that are unused by framebuffer format drm/gem: Warn on trying to use a non-existing framebuffer plane
drivers/gpu/drm/drm_gem_atomic_helper.c | 6 +- drivers/gpu/drm/drm_gem_framebuffer_helper.c | 103 +++++++++---------- drivers/gpu/drm/drm_gem_vram_helper.c | 36 ++++--- include/drm/drm_gem_framebuffer_helper.h | 10 +- 4 files changed, 81 insertions(+), 74 deletions(-)
base-commit: b0b93865a24c910fcbfa6e6fa0955fae930a56d3