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CVE-2022-50488

block, bfq: fix possible uaf for 'bfqq->bic'

High7.8EPSS 0.17%
Published
Updated
Reserved
Assigned by
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: block, bfq: fix possible uaf for 'bfqq->bic' Our test report a uaf for 'bfqq->bic' in 5.10: ================================================================== BUG: KASAN: use-after-free in bfq_select_queue+0x378/0xa30 CPU: 6 PID: 2318352 Comm: fsstress Kdump: loaded Not tainted 5.10.0-60.18.0.50.h602.kasan.eulerosv2r11.x86_64 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-20220320_160524-szxrtosci10000 04/01/2014 Call Trace: bfq_select_queue+0x378/0xa30 bfq_dispatch_request+0xe8/0x130 blk_mq_do_dispatch_sched+0x62/0xb0 __blk_mq_sched_dispatch_requests+0x215/0x2a0 blk_mq_sched_dispatch_requests+0x8f/0xd0 __blk_mq_run_hw_queue+0x98/0x180 __blk_mq_delay_run_hw_queue+0x22b/0x240 blk_mq_run_hw_queue+0xe3/0x190 blk_mq_sched_insert_requests+0x107/0x200 blk_mq_flush_plug_list+0x26e/0x3c0 blk_finish_plug+0x63/0x90 __iomap_dio_rw+0x7b5/0x910 iomap_dio_rw+0x36/0x80 ext4_dio_read_iter+0x146/0x190 [ext4] ext4_file_read_iter+0x1e2/0x230 [ext4] new_sync_read+0x29f/0x400 vfs_read+0x24e/0x2d0 ksys_read+0xd5/0x1b0 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x61/0xc6 Commit 3bc5e683c67d ("bfq: Split shared queues on move between cgroups") changes that move process to a new cgroup will allocate a new bfqq to use, however, the old bfqq and new bfqq can point to the same bic: 1) Initial state, two process with io in the same cgroup. Process 1 Process 2 (BIC1) (BIC2) | Λ | Λ | | | | V | V | bfqq1 bfqq2 2) bfqq1 is merged to bfqq2. Process 1 Process 2 (BIC1) (BIC2) | | \-------------\| V bfqq1 bfqq2(coop) 3) Process 1 exit, then issue new io(denoce IOA) from Process 2. (BIC2) | Λ | | V | bfqq2(coop) 4) Before IOA is completed, move Process 2 to another cgroup and issue io. Process 2 (BIC2) Λ |\--------------\ | V bfqq2 bfqq3 Now that BIC2 points to bfqq3, while bfqq2 and bfqq3 both point to BIC2. If all the requests are completed, and Process 2 exit, BIC2 will be freed while there is no guarantee that bfqq2 will be freed before BIC2. Fix the problem by clearing bfqq->bic while bfqq is detached from bic.

Scores

CVSS scores of CVE-2022-50488, by who scored it
Scored byCVSSScoreVector
LinuxCNA (assigner)3.1High7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVDNVD · Modified3.1High7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (exploitation in 30 days)
0.17% · top 94% of all CVEs (2 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: total

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The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Weakness

Affected products

  • Linux · Linux

    • affected 4dfc12f8c94c8052e975060f595938f75e8b7165 – < 5533742c7cb1bc9b1f0bf401cc397d44a3a9e07a
    • affected 81b7d0c717a487ec50e2924a773ff501ee40f0d5 – < 094f3d9314d67691cb21ba091c1b528f6e3c4893
    • affected 3bc5e683c67d94bd839a1da2e796c15847b51b69 – < b22fd72bfebda3956efc4431b60ddfc0a51e03e0
    • affected 3bc5e683c67d94bd839a1da2e796c15847b51b69 – < 761564d93c8265f65543acf0a576b32d66bfa26a
    • affected 3bc5e683c67d94bd839a1da2e796c15847b51b69 – < 64dc8c732f5c2b406cc752e6aaa1bd5471159cab
    • affected 31326bf551269fb9bafa84ca99172b8340e5d8f8
    • affected 43c51b86dbe551cff5d39b88aa2f41d29479f9c4
    • affected 8615f6c0c9e7cf0ca90b6b5408784d797cbe5621
    • affected 5.10.121 – < 5.10.175
    • affected 5.15.46 – < 5.15.86
    • affected 5.4.198 – < 5.5
    • affected 5.17.14 – < 5.18
    • affected 5.18.3 – < 5.19

  • Linux · Linux

    • affected 5.19
    • unaffected < 5.19
    • unaffected 5.10.175 – ≤ 5.10.*
    • unaffected 5.15.86 – ≤ 5.15.*
    • unaffected 6.0.16 – ≤ 6.0.*
    • unaffected 6.1.2 – ≤ 6.1.*
    • unaffected 6.2 – ≤ *

References (5)

Sources

The same CVE in the primary databases and aggregators, to check against.

Record last updated .