{"cve":"CVE-2026-72420","nvd":{"published":"2026-08-15T06:22:15.743","modified":"2026-10-21T13:19:37.580","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmd/raid5: avoid R5_Overlap races while breaking stripe batches\n\nKCSAN report a race in break_stripe_batch_list() vs. raid5_make_request()\non sh->dev[i].flags (plain word write vs. atomic bit op)..\n\nand .. one possible scenario is:\n\nCPU1                            CPU2\nbreak_stripe_batch_list(sh1)\n-> handle sh2\n-> lock(sh2)\n-> sh2->batch_head = NULL\n-> unlock(sh2)\n-> test_and_clear_bit(R5_Overlap, sh2->dev[i].flags)\n-> wake_up_bit(sh2->dev[i].flags)\n                                raid5_make_request()\n                                -> add_all_stripe_bios(sh2)\n                                -> lock(sh2)\n                                -> stripe_bio_overlaps(sh2) returns true\n\t\t\t\t   batch_head is NULL, so new bio overlap\n\t\t\t\t   exist bio on sh2 -> true\n                                -> set_bit(R5_Overlap, sh2->dev[i].flags)\n                                -> unlock(sh2)\n                                -> wait_on_bit(sh2->dev[i].flags)\n-> sh2->dev[i].flags = sh1->dev[i].flags & ~R5_Overlap\n\nNo wait_up_bit(), CPU2 could be wait_on_bit() forever...\n\nFix by :\n- Expand the protect zone.\n- Use batch_head's device flag's snaphot when no held head_sh->stripe_lock.\n- Move sh/head_sh->batch_head = NULL to the end of protected zone , and ,\n  any concurrent add_all_stripe_bios() grabs sh->stripe_lock now either:\n\t- see batch_head != null, and , is rejected by stripe_bio_overlaps()\n\t  under the lock (no R5_Overlap wait ) , or ,\n\t- sees batch_head == NULL, only after dev[i].flags has already been\n\t  set and the prior R5_Overlap waiters worken.\n\nKCSAN report:\n================================================\n  BUG: KCSAN: data-race in break_stripe_batch_list / raid5_make_request\n\n  write (marked) to 0xffff8e89c8117548 of 8 bytes by task 4042 on cpu 0:\n    raid5_make_request+0xea0/0x2930\n    md_handle_request+0x4a2/0xa40\n    md_submit_bio+0x109/0x1a0\n    __submit_bio+0x2ec/0x390\n    submit_bio_noacct_nocheck+0x457/0x710\n    submit_bio_noacct+0x2a7/0xc20\n    submit_bio+0x56/0x250\n    blkdev_direct_IO+0x54c/0xda0\n    blkdev_write_iter+0x38f/0x570\n    aio_write+0x22b/0x490\n    io_submit_one+0xa51/0xf70\n    __x64_sys_io_submit+0xf7/0x220\n    x64_sys_call+0x1907/0x1c60\n    do_syscall_64+0x130/0x570\n    entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\n  read to 0xffff8e89c8117548 of 8 bytes by task 4010 on cpu 5:\n    break_stripe_batch_list+0x249/0x480\n    handle_stripe_clean_event+0x720/0x9b0\n    handle_stripe+0x32fb/0x4500\n    handle_active_stripes.isra.0+0x6e0/0xa50\n    raid5d+0x7e0/0xba0\n    md_thread+0x15a/0x2d0\n    kthread+0x1e3/0x220\n    ret_from_fork+0x37a/0x410\n    ret_from_fork_asm+0x1a/0x30\n\n  value changed: 0x0000000000000019 -> 0x0000000000000099 --> R5_Overlap","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":[],"references":["https://git.kernel.org/stable/c/158a5480d51969adeb727ff20c6fa96f063e9f9e","https://git.kernel.org/stable/c/4d919c9b770996365806b6c8d701912d52baa306","https://git.kernel.org/stable/c/55b77337bdd088c77461588e5ec094421b89911b","https://git.kernel.org/stable/c/8031b0d02bd221a5f9add4357e291fc2a527b83a","https://git.kernel.org/stable/c/d684b72dfbd320623ccaab0779aa841190488e7c"],"products":[],"source":"nvd","synced_at":"2026-10-22T16:41:11.231219466+00:00"},"epss":{"cve":"CVE-2026-72420","score":0.00601,"percentile":0.4845,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}