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CVE-2022-49394— blk-iolatency: Fix inflight count imbalances and IO hangs on offline

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于iolatency_pd_offline函数在未冻结队列时减少enabled计数器，导致inflight计数不平衡和IO挂起。

AI Predicted 7.5 Difficulty: Hard EPSS 0.27% · P18

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 19

VendorProduct Version RangeStatus
Linux Linux 6d482bc5697763eb1214f207286daa201b32d20a< 515d077ee3085ae343b6bea7fd031f9906645f38 affected
8c772a9bfc7c07c76f4a58b58910452fbb20843b< d19fa8f252000d141f9199ca32959c50314e1f05 affected
8c772a9bfc7c07c76f4a58b58910452fbb20843b< 77692c02e1517c54f2fd0535f41aa4286ac9f140 affected
8c772a9bfc7c07c76f4a58b58910452fbb20843b< a30acbb5dfb7bcc813ad6a18ca31011ac44e5547 affected
8c772a9bfc7c07c76f4a58b58910452fbb20843b< 968f7a239c590454ffba79c126fbe0e963a0ba78 affected
8c772a9bfc7c07c76f4a58b58910452fbb20843b< 5b0ff3ebbef791341695b718f8d2870869cf1d01 affected
8c772a9bfc7c07c76f4a58b58910452fbb20843b< 8a177a36da6c54c98b8685d4f914cb3637d53c0d affected
beed6109acd4efc2f1717c31bddcd0ad7ebbf253 affected
… +11 more rows
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I. Basic Information for CVE-2022-49394

Vulnerability Information
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Vulnerability Title
blk-iolatency: Fix inflight count imbalances and IO hangs on offline
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: blk-iolatency: Fix inflight count imbalances and IO hangs on offline iolatency needs to track the number of inflight IOs per cgroup. As this tracking can be expensive, it is disabled when no cgroup has iolatency configured for the device. To ensure that the inflight counters stay balanced, iolatency_set_limit() freezes the request_queue while manipulating the enabled counter, which ensures that no IO is in flight and thus all counters are zero. Unfortunately, iolatency_set_limit() isn't the only place where the enabled counter is manipulated. iolatency_pd_offline() can also dec the counter and trigger disabling. As this disabling happens without freezing the q, this can easily happen while some IOs are in flight and thus leak the counts. This can be easily demonstrated by turning on iolatency on an one empty cgroup while IOs are in flight in other cgroups and then removing the cgroup. Note that iolatency shouldn't have been enabled elsewhere in the system to ensure that removing the cgroup disables iolatency for the whole device. The following keeps flipping on and off iolatency on sda: echo +io > /sys/fs/cgroup/cgroup.subtree_control while true; do mkdir -p /sys/fs/cgroup/test echo '8:0 target=100000' > /sys/fs/cgroup/test/io.latency sleep 1 rmdir /sys/fs/cgroup/test sleep 1 done and there's concurrent fio generating direct rand reads: fio --name test --filename=/dev/sda --direct=1 --rw=randread \ --runtime=600 --time_based --iodepth=256 --numjobs=4 --bs=4k while monitoring with the following drgn script: while True: for css in css_for_each_descendant_pre(prog['blkcg_root'].css.address_of_()): for pos in hlist_for_each(container_of(css, 'struct blkcg', 'css').blkg_list): blkg = container_of(pos, 'struct blkcg_gq', 'blkcg_node') pd = blkg.pd[prog['blkcg_policy_iolatency'].plid] if pd.value_() == 0: continue iolat = container_of(pd, 'struct iolatency_grp', 'pd') inflight = iolat.rq_wait.inflight.counter.value_() if inflight: print(f'inflight={inflight} {disk_name(blkg.q.disk).decode("utf-8")} ' f'{cgroup_path(css.cgroup).decode("utf-8")}') time.sleep(1) The monitoring output looks like the following: inflight=1 sda /user.slice inflight=1 sda /user.slice ... inflight=14 sda /user.slice inflight=13 sda /user.slice inflight=17 sda /user.slice inflight=15 sda /user.slice inflight=18 sda /user.slice inflight=17 sda /user.slice inflight=20 sda /user.slice inflight=19 sda /user.slice <- fio stopped, inflight stuck at 19 inflight=19 sda /user.slice inflight=19 sda /user.slice If a cgroup with stuck inflight ends up getting throttled, the throttled IOs will never get issued as there's no completion event to wake it up leading to an indefinite hang. This patch fixes the bug by unifying enable handling into a work item which is automatically kicked off from iolatency_set_min_lat_nsec() which is called from both iolatency_set_limit() and iolatency_pd_offline() paths. Punting to a work item is necessary as iolatency_pd_offline() is called under spinlocks while freezing a request_queue requires a sleepable context. This also simplifies the code reducing LOC sans the comments and avoids the unnecessary freezes which were happening whenever a cgroup's latency target is newly set or cleared.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于iolatency_pd_offline函数在未冻结队列时减少enabled计数器，导致inflight计数不平衡和IO挂起。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 6d482bc5697763eb1214f207286daa201b32d20a ~ 515d077ee3085ae343b6bea7fd031f9906645f38 -
Linux Linux 5.0 -

II. Public POCs for CVE-2022-49394

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III. Intelligence Information for CVE-2022-49394

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Patches & Fixes for CVE-2022-49394 (7)

Same Patch Batch · Linux · 2025-02-26 · 706 CVEs total

CVE-2022-49561 9.8 CRITICAL netfilter: conntrack: re-fetch conntrack after insertion
CVE-2022-49149 9.8 CRITICAL rxrpc: Fix call timer start racing with call destruction
CVE-2022-49407 9.8 CRITICAL dlm: fix plock invalid read
CVE-2022-49362 9.8 CRITICAL NFSD: Fix potential use-after-free in nfsd_file_put()
CVE-2022-49201 9.8 CRITICAL ibmvnic: fix race between xmit and reset
CVE-2022-49194 9.8 CRITICAL net: bcmgenet: Use stronger register read/writes to assure ordering
CVE-2022-49093 9.8 CRITICAL skbuff: fix coalescing for page_pool fragment recycling
CVE-2022-49260 9.8 CRITICAL crypto: hisilicon/sec - fix the aead software fallback for engine
CVE-2022-49094 9.8 CRITICAL net/tls: fix slab-out-of-bounds bug in decrypt_internal
CVE-2022-49418 9.8 CRITICAL NFSv4: Fix free of uninitialized nfs4_label on referral lookup.
CVE-2022-49280 9.8 CRITICAL NFSD: prevent underflow in nfssvc_decode_writeargs()
CVE-2022-49356 9.8 CRITICAL SUNRPC: Trap RDMA segment overflows
CVE-2022-49058 9.1 CRITICAL cifs: potential buffer overflow in handling symlinks
CVE-2022-49500 8.8 HIGH wl1251: dynamically allocate memory used for DMA
CVE-2022-49470 8.8 HIGH Bluetooth: btmtksdio: fix use-after-free at btmtksdio_recv_event
CVE-2022-49114 8.8 HIGH scsi: libfc: Fix use after free in fc_exch_abts_resp()
CVE-2022-49535 8.8 HIGH scsi: lpfc: Fix null pointer dereference after failing to issue FLOGI and PLOGI
CVE-2022-49471 8.8 HIGH rtw89: cfo: check mac_id to avoid out-of-bounds
CVE-2022-49111 8.8 HIGH Bluetooth: Fix use after free in hci_send_acl
CVE-2022-49519 8.8 HIGH ath10k: skip ath10k_halt during suspend for driver state RESTARTING

Showing top 20 of 706 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

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Same vendor: Linux

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