{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72420", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.927Z", "datePublished": "2026-08-15T05:56:39.802Z", "dateUpdated": "2026-08-17T05:44:00.561Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:44:00.561Z" }, "descriptions": [ { "lang": "en", "value": "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" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - RAID5/md arrays commonly back internet-facing NAS and SAN servers; remote writes via NFS, SMB (ksmbd), or iSCSI/NVMe-oF targets reach raid5_make_request() through the server block layer when flushing data to the array.\nAC:L - The KCSAN race needs concurrent full-stripe writes during batch teardown; an attacker can reliably drive both sides with parallel aio/io_submit or network storage clients hammering the same stripes without depending on uncontrollable timing or rare kernel configs.\nPR:L - Exploitation requires only permission to issue writes that hit the RAID5 device (e.g., a storage client account, local user writing to a filesystem on /dev/md*, or block-device access), not init-namespace root or CAP_SYS_ADMIN on the host.\nUI:N - Triggering the race is fully automated through concurrent I/O requests; no victim click, mount, or other interactive action beyond the attacker's own write traffic is required.\nS:U - Impact is confined to kernel RAID5 I/O handling and data on the affected host or its directly attached arrays; it does not cross VM, container, or IOMMU security boundaries.\nC:H - KCSAN documents a data race on r5dev->flags where break_stripe_batch_list() plain-writes the whole flags word concurrent with atomic bitops, which can corrupt R5_UPTODATE/R5_Insync state and expose stale stripe cache contents to readers.\nI:H - The same non-atomic flags overwrite can desynchronize stripe bookkeeping and in-flight write state during batch break, enabling incorrect parity/rebuild decisions and corrupted or misdirected full-stripe writes to RAID member devices.\nA:H - The documented failure leaves raid5_make_request() threads stuck in TASK_UNINTERRUPTIBLE wait_on_bit() forever when R5_Overlap is cleared without wake_up_bit(), hanging I/O workers and enabling repeatable denial of storage service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/md/raid5.c" ], "versions": [ { "version": "fb642b92c267beeefd352af9bc461eac93a7552c", "lessThan": "8031b0d02bd221a5f9add4357e291fc2a527b83a", "status": "affected", "versionType": "git" }, { "version": "fb642b92c267beeefd352af9bc461eac93a7552c", "lessThan": "4d919c9b770996365806b6c8d701912d52baa306", "status": "affected", "versionType": "git" }, { "version": "fb642b92c267beeefd352af9bc461eac93a7552c", "lessThan": "d684b72dfbd320623ccaab0779aa841190488e7c", "status": "affected", "versionType": "git" }, { "version": "fb642b92c267beeefd352af9bc461eac93a7552c", "lessThan": "55b77337bdd088c77461588e5ec094421b89911b", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/md/raid5.c" ], "versions": [ { "version": "4.1", "status": "affected" }, { "version": "0", "lessThan": "4.1", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8031b0d02bd221a5f9add4357e291fc2a527b83a" }, { "url": "https://git.kernel.org/stable/c/4d919c9b770996365806b6c8d701912d52baa306" }, { "url": "https://git.kernel.org/stable/c/d684b72dfbd320623ccaab0779aa841190488e7c" }, { "url": "https://git.kernel.org/stable/c/55b77337bdd088c77461588e5ec094421b89911b" } ], "title": "md/raid5: avoid R5_Overlap races while breaking stripe batches", "x_generator": { "engine": "bippy-1.2.0" } } } }