{"id":"CVE-2026-43288","summary":"ext4: move ext4_percpu_param_init() before ext4_mb_init()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: move ext4_percpu_param_init() before ext4_mb_init()\n\nWhen running `kvm-xfstests -c ext4/1k -C 1 generic/383` with the\n`DOUBLE_CHECK` macro defined, the following panic is triggered:\n\n==================================================================\nEXT4-fs error (device vdc): ext4_validate_block_bitmap:423:\n                        comm mount: bg 0: bad block bitmap checksum\nBUG: unable to handle page fault for address: ff110000fa2cc000\nPGD 3e01067 P4D 3e02067 PUD 0\nOops: Oops: 0000 [#1] SMP NOPTI\nCPU: 0 UID: 0 PID: 2386 Comm: mount Tainted: G W\n                        6.18.0-gba65a4e7120a-dirty #1152 PREEMPT(none)\nRIP: 0010:percpu_counter_add_batch+0x13/0xa0\nCall Trace:\n \u003cTASK\u003e\n ext4_mark_group_bitmap_corrupted+0xcb/0xe0\n ext4_validate_block_bitmap+0x2a1/0x2f0\n ext4_read_block_bitmap+0x33/0x50\n mb_group_bb_bitmap_alloc+0x33/0x80\n ext4_mb_add_groupinfo+0x190/0x250\n ext4_mb_init_backend+0x87/0x290\n ext4_mb_init+0x456/0x640\n __ext4_fill_super+0x1072/0x1680\n ext4_fill_super+0xd3/0x280\n get_tree_bdev_flags+0x132/0x1d0\n vfs_get_tree+0x29/0xd0\n vfs_cmd_create+0x59/0xe0\n __do_sys_fsconfig+0x4f6/0x6b0\n do_syscall_64+0x50/0x1f0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n==================================================================\n\nThis issue can be reproduced using the following commands:\n        mkfs.ext4 -F -q -b 1024 /dev/sda 5G\n        tune2fs -O quota,project /dev/sda\n        mount /dev/sda /tmp/test\n\nWith DOUBLE_CHECK defined, mb_group_bb_bitmap_alloc() reads\nand validates the block bitmap. When the validation fails,\next4_mark_group_bitmap_corrupted() attempts to update\nsbi-\u003es_freeclusters_counter. However, this percpu_counter has not been\ninitialized yet at this point, which leads to the panic described above.\n\nFix this by moving the execution of ext4_percpu_param_init() to occur\nbefore ext4_mb_init(), ensuring the per-CPU counters are initialized\nbefore they are used.","modified":"2026-06-18T03:55:50.171845826Z","published":"2026-05-08T13:11:13.195Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43288.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0d5fcb063cdabb9aeaa8554b7fedad2092c4150e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/270564513489d98b721a1e4a10017978d5213bff"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9e9fb259bcddf459a0168f4a964e979e500a68a5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aec095f3cc6cf209effd93278ce35be27db81d73"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bf5b609524497c195f801cd5707252384aed8149"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43288.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43288"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"d5e03cbb0c88cd1be39f2adc37d602230045964b"},{"fixed":"0d5fcb063cdabb9aeaa8554b7fedad2092c4150e"},{"fixed":"9e9fb259bcddf459a0168f4a964e979e500a68a5"},{"fixed":"bf5b609524497c195f801cd5707252384aed8149"},{"fixed":"aec095f3cc6cf209effd93278ce35be27db81d73"},{"fixed":"270564513489d98b721a1e4a10017978d5213bff"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-43288.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.17.0"},{"fixed":"6.6.128"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.75"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.16"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-43288.json"}}],"schema_version":"1.7.5"}