{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2022-50488", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-10-04T15:13:33.468Z", "datePublished": "2025-10-04T15:43:42.352Z", "dateUpdated": "2026-08-05T08:58:55.457Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:58:55.457Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock, bfq: fix possible uaf for 'bfqq->bic'\n\nOur test report a uaf for 'bfqq->bic' in 5.10:\n\n==================================================================\nBUG: KASAN: use-after-free in bfq_select_queue+0x378/0xa30\n\nCPU: 6 PID: 2318352 Comm: fsstress Kdump: loaded Not tainted 5.10.0-60.18.0.50.h602.kasan.eulerosv2r11.x86_64 #1\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-20220320_160524-szxrtosci10000 04/01/2014\nCall Trace:\n bfq_select_queue+0x378/0xa30\n bfq_dispatch_request+0xe8/0x130\n blk_mq_do_dispatch_sched+0x62/0xb0\n __blk_mq_sched_dispatch_requests+0x215/0x2a0\n blk_mq_sched_dispatch_requests+0x8f/0xd0\n __blk_mq_run_hw_queue+0x98/0x180\n __blk_mq_delay_run_hw_queue+0x22b/0x240\n blk_mq_run_hw_queue+0xe3/0x190\n blk_mq_sched_insert_requests+0x107/0x200\n blk_mq_flush_plug_list+0x26e/0x3c0\n blk_finish_plug+0x63/0x90\n __iomap_dio_rw+0x7b5/0x910\n iomap_dio_rw+0x36/0x80\n ext4_dio_read_iter+0x146/0x190 [ext4]\n ext4_file_read_iter+0x1e2/0x230 [ext4]\n new_sync_read+0x29f/0x400\n vfs_read+0x24e/0x2d0\n ksys_read+0xd5/0x1b0\n do_syscall_64+0x33/0x40\n entry_SYSCALL_64_after_hwframe+0x61/0xc6\n\nCommit 3bc5e683c67d (\"bfq: Split shared queues on move between cgroups\")\nchanges that move process to a new cgroup will allocate a new bfqq to\nuse, however, the old bfqq and new bfqq can point to the same bic:\n\n1) Initial state, two process with io in the same cgroup.\n\nProcess 1 Process 2\n (BIC1) (BIC2)\n | Λ | Λ\n | | | |\n V | V |\n bfqq1 bfqq2\n\n2) bfqq1 is merged to bfqq2.\n\nProcess 1 Process 2\n (BIC1) (BIC2)\n | |\n \\-------------\\|\n V\n bfqq1 bfqq2(coop)\n\n3) Process 1 exit, then issue new io(denoce IOA) from Process 2.\n\n (BIC2)\n | Λ\n | |\n V |\n bfqq2(coop)\n\n4) Before IOA is completed, move Process 2 to another cgroup and issue io.\n\nProcess 2\n (BIC2)\n Λ\n |\\--------------\\\n | V\n bfqq2 bfqq3\n\nNow that BIC2 points to bfqq3, while bfqq2 and bfqq3 both point to BIC2.\nIf all the requests are completed, and Process 2 exit, BIC2 will be\nfreed while there is no guarantee that bfqq2 will be freed before BIC2.\n\nFix the problem by clearing bfqq->bic while bfqq is detached from bic." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached through local block I/O on a BFQ-scheduled device (read/write syscalls → blk-mq → bfq_select_queue) plus local cgroup migration of the attacking processes; it is not reachable from network packet processing.\nAC:L - An attacker who controls cooperating processes can drive queue merging (including early stable merge), keep I/O outstanding, migrate those tasks between cgroups they can write, and exit to free the bic—so both sides of the race and the trigger sequence are attacker-controlled.\nPR:L - Only an unprivileged local account is required to issue I/O; cgroup moves needed for the split path are available to low-privilege users via delegated cgroup subtrees (containers, systemd Delegate, nsdelegate), which does not require real root in the init namespace.\nUI:N - Exploitation uses the attacker’s own processes, I/O, cgroup.procs writes, and exits; no separate victim action is required.\nS:U - This is a kernel-heap use-after-free that enables privilege escalation within the same OS security authority, not a VM/IOMMU/sandbox boundary cross.\nC:H - bfq_select_queue dereferences the freed bic (e.g. bfqq->bic->bfqq[0]); reclaiming the bfq_io_cq slab object yields a strong read primitive over attacker-controlled contents.\nI:H - The same UAF on a pointer-rich bic object is exploitable via heap spray to forge queue pointers and obtain arbitrary write / control-flow hijacking in the kernel.\nA:H - Use of the dangling bfqq->bic causes kernel KASAN/UAF faults and oopses (as in the reported bfq_select_queue crash), so availability impact is complete." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "block/bfq-iosched.c" ], "versions": [ { "version": "4dfc12f8c94c8052e975060f595938f75e8b7165", "lessThan": "5533742c7cb1bc9b1f0bf401cc397d44a3a9e07a", "status": "affected", "versionType": "git" }, { "version": "81b7d0c717a487ec50e2924a773ff501ee40f0d5", "lessThan": "094f3d9314d67691cb21ba091c1b528f6e3c4893", "status": "affected", "versionType": "git" }, { "version": "3bc5e683c67d94bd839a1da2e796c15847b51b69", "lessThan": "b22fd72bfebda3956efc4431b60ddfc0a51e03e0", "status": "affected", "versionType": "git" }, { "version": "3bc5e683c67d94bd839a1da2e796c15847b51b69", "lessThan": "761564d93c8265f65543acf0a576b32d66bfa26a", "status": "affected", "versionType": "git" }, { "version": "3bc5e683c67d94bd839a1da2e796c15847b51b69", "lessThan": "64dc8c732f5c2b406cc752e6aaa1bd5471159cab", "status": "affected", "versionType": "git" }, { "version": "31326bf551269fb9bafa84ca99172b8340e5d8f8", "status": "affected", "versionType": "git" }, { "version": "43c51b86dbe551cff5d39b88aa2f41d29479f9c4", "status": "affected", "versionType": "git" }, { "version": "8615f6c0c9e7cf0ca90b6b5408784d797cbe5621", "status": "affected", "versionType": "git" }, { "version": "5.10.121", "lessThan": "5.10.175", "status": "affected", "versionType": "semver" }, { "version": "5.15.46", "lessThan": "5.15.86", "status": "affected", "versionType": "semver" }, { "version": "5.4.198", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "5.17.14", "lessThan": "5.18", "status": "affected", "versionType": "semver" }, { "version": "5.18.3", "lessThan": "5.19", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "block/bfq-iosched.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.175", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.86", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.0.16", "lessThanOrEqual": "6.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.2", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.2", "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": "5.10.121", "versionEndExcluding": "5.10.175" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.46", "versionEndExcluding": "5.15.86" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.0.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.1.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.198" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5533742c7cb1bc9b1f0bf401cc397d44a3a9e07a" }, { "url": "https://git.kernel.org/stable/c/094f3d9314d67691cb21ba091c1b528f6e3c4893" }, { "url": "https://git.kernel.org/stable/c/b22fd72bfebda3956efc4431b60ddfc0a51e03e0" }, { "url": "https://git.kernel.org/stable/c/761564d93c8265f65543acf0a576b32d66bfa26a" }, { "url": "https://git.kernel.org/stable/c/64dc8c732f5c2b406cc752e6aaa1bd5471159cab" } ], "title": "block, bfq: fix possible uaf for 'bfqq->bic'", "x_generator": { "engine": "bippy-1.2.0" } } } }