4b848f20ed
There's two references floating around here (for the object reference, not the handle_count reference, that's a different thing): - The temporary reference held by vgem_gem_create, acquired by creating the object and released by calling drm_gem_object_put_unlocked. - The reference held by the object handle, created by drm_gem_handle_create. This one generally outlives the function, except if a 2nd thread races with a GEM_CLOSE ioctl call. So usually everything is correct, except in that race case, where the access to gem_object->size could be looking at freed data already. Which again isn't a real problem (userspace shot its feet off already with the race, we could return garbage), but maybe someone can exploit this as an information leak. Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Hillf Danton <hdanton@sina.com> Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Cc: Emil Velikov <emil.velikov@collabora.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Sean Paul <seanpaul@chromium.org> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Eric Anholt <eric@anholt.net> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Rob Clark <robdclark@chromium.org> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200202132133.1891846-1-daniel.vetter@ffwll.ch |
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| Makefile | ||
| vgem_drv.c | ||
| vgem_drv.h | ||
| vgem_fence.c | ||