{"id":"CVE-2026-99007","published":"2026-10-23T13:17:23.157","lastModified":"2026-10-23T13:17:23.157","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN\n\n__drm_fb_helper_initial_config_and_unlock() calls\ndrm_client_modeset_probe() first, which already fills in each\nmode_set->mode/num_connectors for every connected output, and only\nafterwards calls drm_fb_helper_single_fb_probe() to create\nfb_helper->fb and wire it into those mode_sets via\ndrm_setup_crtcs_fb().\n\nIf drm_fb_helper_single_fb_probe() fails with anything other than\n-EAGAIN (e.g. dev->driver->fbdev_probe() itself fails), the function\nbails out before drm_setup_crtcs_fb() runs and before setting\nfb_helper->deferred_setup. The client is left with mode_sets that\nhave a mode and connectors but mode_set->fb == NULL, and nothing\nmarks this fb_helper as needing a retry.\n\n__drm_fb_helper_restore_fbdev_mode_unlocked() only skips committing\nwhen fb_helper->deferred_setup is set, so a later .restore() call\n(drm_lastclose() on process exit, in this report) commits the stale\nmode_set through drm_client_modeset_commit() ->\ndrm_client_modeset_commit_atomic() -> __drm_atomic_helper_set_config(),\nwhich hits WARN_ON(!set->fb).\n\nMark fb_helper->deferred_setup on any drm_fb_helper_single_fb_probe()\nfailure, not just -EAGAIN, so restore keeps skipping the commit until\na later hotplug event successfully re-probes and re-populates\nmode_set->fb. The real error code is still returned to the caller\nunchanged.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/3b303696f61461b3569019d7fcac6a646652b2b4","tags":[]},{"url":"https://git.kernel.org/stable/c/4a2006c675758f0c765b36fec6b49d17e89159cf","tags":[]},{"url":"https://git.kernel.org/stable/c/4e7b508c7c60dec7a86b7eb2a1b7e6d174afa457","tags":[]},{"url":"https://git.kernel.org/stable/c/755c94d178b7e972bb766199d34e4ba4f63a89eb","tags":[]},{"url":"https://git.kernel.org/stable/c/d510ed273854177f0a3ed330145858b2fe667f81","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}