{"id":"CVE-2025-40323","revision":"6d8ec0a004d745f5a302db5aaa2223c0","records":[{"revision":"6d8ec0a004d745f5a302db5aaa2223c0","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-40323","aliases":[],"title":"fbcon: Set fb_display[i]->mode to NULL when the mode is released","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfbcon: Set fb_display[i]->mode to NULL when the mode is released\n\nRecently, we discovered the following issue through syzkaller:\n\nBUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0\nRead of size 4 at addr ff11000001b3c69c by task syz.xxx\n...\nCall Trace:\n \n dump_stack_lvl+0xab/0xe0\n print_address_description.constprop.0+0x2c/0x390\n print_report+0xb9/0x280\n kasan_report+0xb8/0xf0\n fb_mode_is_equal+0x285/0x2f0\n fbcon_mode_deleted+0x129/0x180\n fb_set_var+0xe7f/0x11d0\n do_fb_ioctl+0x6a0/0x750\n fb_ioctl+0xe0/0x140\n __x64_sys_ioctl+0x193/0x210\n do_syscall_64+0x5f/0x9c0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nBased on experimentation and analysis, during framebuffer unregistration,\nonly the memory of fb_info->modelist is freed, without setting the\ncorresponding fb_display[i]->mode to NULL for the freed modes. This leads\nto UAF issues during subsequent accesses. Here's an example of reproduction\nsteps:\n1. With /dev/fb0 already registered in the system, load a kernel module\n to register a new device /dev/fb1;\n2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP);\n3. Switch console from fb to VGA (to allow normal rmmod of the ko);\n4. Unload the kernel module, at this point fb1's modelist is freed, leaving\n a wild pointer in fb_display[];\n5. Trigger the bug via system calls through fb0 attempting to delete a mode\n from fb0.\n\nAdd a check in do_unregister_framebuffer(): if the mode to be freed exists\nin fb_display[], set the corresponding mode pointer to NULL.","state":0,"publishedAt":"2025-12-08T00:46:50.833+00:00","modifiedAt":"2026-10-15T22:02:45.798+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/video/fbdev/core/fbcon.c\",\n \"drivers/video/fbdev/core/fbmem.c\",\n \"include/linux/fbcon.h\"\n ],\n \"versions\": [\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"39c2c1a2773aaf73e56906e5ef670114eb2d354f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"468f78276a37f4c6499385a4ce28f4f57be6655d\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"c079d42f70109512eee49123a843be91d8fa133f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"de89d19f4f30d9a8de87b9d08c1bd35cb70576d8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"a1f3058930745d2b938b6b4f5bd9630dc74b26b7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/video/fbdev/core/fbcon.c\",\n \"drivers/video/fbdev/core/fbmem.c\",\n \"include/linux/fbcon.h\"\n ],\n \"versions\": [\n {\n \"version\": \"2.6.12\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"2.6.12\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.203\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.159\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.117\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.58\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.17.8\",\n \"lessThanOrEqual\": \"6.17.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/39c2c1a2773aaf73e56906e5ef670114eb2d354f","https://git.kernel.org/stable/c/4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb","https://git.kernel.org/stable/c/468f78276a37f4c6499385a4ce28f4f57be6655d","https://git.kernel.org/stable/c/c079d42f70109512eee49123a843be91d8fa133f","https://git.kernel.org/stable/c/de89d19f4f30d9a8de87b9d08c1bd35cb70576d8","https://git.kernel.org/stable/c/a1f3058930745d2b938b6b4f5bd9630dc74b26b7"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-40323","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-40323","identifiers":["CVE-2025-40323"]},"retained":false,"historicalAffected":[]}],"coverage":[]}