{"id":"CVE-2025-38621","summary":"md: make rdev_addable usable for rcu mode","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmd: make rdev_addable usable for rcu mode\n\nOur testcase trigger panic:\n\nBUG: kernel NULL pointer dereference, address: 00000000000000e0\n...\nOops: Oops: 0000 [#1] SMP NOPTI\nCPU: 2 UID: 0 PID: 85 Comm: kworker/2:1 Not tainted 6.16.0+ #94\nPREEMPT(none)\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.16.1-2.fc37 04/01/2014\nWorkqueue: md_misc md_start_sync\nRIP: 0010:rdev_addable+0x4d/0xf0\n...\nCall Trace:\n \u003cTASK\u003e\n md_start_sync+0x329/0x480\n process_one_work+0x226/0x6d0\n worker_thread+0x19e/0x340\n kthread+0x10f/0x250\n ret_from_fork+0x14d/0x180\n ret_from_fork_asm+0x1a/0x30\n \u003c/TASK\u003e\nModules linked in: raid10\nCR2: 00000000000000e0\n---[ end trace 0000000000000000 ]---\nRIP: 0010:rdev_addable+0x4d/0xf0\n\nmd_spares_need_change in md_start_sync will call rdev_addable which\nprotected by rcu_read_lock/rcu_read_unlock. This rcu context will help\nprotect rdev won't be released, but rdev-\u003emddev will be set to NULL\nbefore we call synchronize_rcu in md_kick_rdev_from_array. Fix this by\nusing READ_ONCE and check does rdev-\u003emddev still alive.","modified":"2026-04-02T12:48:03.136325Z","published":"2025-08-22T16:00:30.308Z","related":["CGA-8xjc-gqgh-pj2q","SUSE-SU-2025:03272-1","SUSE-SU-2025:03290-1","SUSE-SU-2025:03301-1","SUSE-SU-2025:03382-1","SUSE-SU-2025:03602-1","SUSE-SU-2025:03633-1","SUSE-SU-2025:03634-1","SUSE-SU-2025:20653-1","SUSE-SU-2025:20669-1","SUSE-SU-2025:20739-1","SUSE-SU-2025:20756-1","SUSE-SU-2025:21074-1","SUSE-SU-2025:21139-1","SUSE-SU-2025:21179-1","openSUSE-SU-2025:20081-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38621.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/13017b427118f4311471ee47df74872372ca8482"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b5fbe940862339cdcc34dea7a057ad18d18fa137"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38621.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38621"},{"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":"bc08041b32abe6c9824f78735bac22018eabfc06"},{"fixed":"b5fbe940862339cdcc34dea7a057ad18d18fa137"},{"fixed":"13017b427118f4311471ee47df74872372ca8482"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38621.json"}}],"schema_version":"1.7.5"}