{"id":"CVE-2026-99007","title":"drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN","summary":"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 alre…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 4a2006c675758f0c765b36fec6b49d17e89159cf","Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 3b303696f61461b3569019d7fcac6a646652b2b4","Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 4e7b508c7c60dec7a86b7eb2a1b7e6d174afa457","Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < d510ed273854177f0a3ed330145858b2fe667f81","Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 755c94d178b7e972bb766199d34e4ba4f63a89eb","Linux 4.14"],"published":"2026-10-23","updated":"2026-10-23","sourceUpdated":"2026-10-23T12:20:32.381Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99007","references":[{"url":"https://git.kernel.org/stable/c/4a2006c675758f0c765b36fec6b49d17e89159cf"},{"url":"https://git.kernel.org/stable/c/3b303696f61461b3569019d7fcac6a646652b2b4"},{"url":"https://git.kernel.org/stable/c/4e7b508c7c60dec7a86b7eb2a1b7e6d174afa457"},{"url":"https://git.kernel.org/stable/c/d510ed273854177f0a3ed330145858b2fe667f81"},{"url":"https://git.kernel.org/stable/c/755c94d178b7e972bb766199d34e4ba4f63a89eb"}],"tags":["cve.org"],"ingestedAt":"2026-10-23T13:24:55.540Z","slug":"CVE-2026-99007","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 4a2006c675758f0c765b36fec6b49d17e89159cf`\n- `Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 3b303696f61461b3569019d7fcac6a646652b2b4`\n- `Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 4e7b508c7c60dec7a86b7eb2a1b7e6d174afa457`\n- `Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < d510ed273854177f0a3ed330145858b2fe667f81`\n- `Linux >= ca91a2758fcef6635626993557dd51cfbb6dd134 < 755c94d178b7e972bb766199d34e4ba4f63a89eb`\n- `Linux 4.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}