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CVE-2022-50335— 9p: set req refcount to zero to avoid uninitialized usage

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，该漏洞源于未初始化请求引用计数，可能导致使用未初始化的请求数据结构。

CVSS 9.8 · Critical EPSS 0.38% · P31 Updated Aug 05, 2026

Possible ATT&CK Techniques 3 AI

T1068 · Exploitation for Privilege Escalation T1053 · Scheduled Task/Job T1564 · Hide Artifacts

Affected Version Matrix 12

Vendor	Product	Version Range	Status
Linux	Linux	`728356dedeff8ef999cb436c71333ef4ac51a81c< 1cabce56626a61f4f02452cba61ad4332a4b73f8`	affected
		`728356dedeff8ef999cb436c71333ef4ac51a81c< 73c47b3123b351de2d3714a72a336c0f72f203af`	affected
		`728356dedeff8ef999cb436c71333ef4ac51a81c< 967fc34f297e40fd2e068cf6b0c3eb4916228539`	affected
		`728356dedeff8ef999cb436c71333ef4ac51a81c< 26273ade77f54716e30dfd40ac6e85ceb54ac0f9`	affected
		`3665a4d9dca1bd06bc34afb72e637fe01b2776ee`	affected
		`4.19.57< 4.20`	affected
		`4.20`	affected
		`< 4.20`	unaffected
… +4 more rows

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I. Basic Information for CVE-2022-50335

Vulnerability Information

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Vulnerability Title

9p: set req refcount to zero to avoid uninitialized usage

Source: CVE Program / CVE List V5

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: 9p: set req refcount to zero to avoid uninitialized usage When a new request is allocated, the refcount will be zero if it is reused, but if the request is newly allocated from slab, it is not fully initialized before being added to idr. If the p9_read_work got a response before the refcount initiated. It will use a uninitialized req, which will result in a bad request data struct. Here is the logs from syzbot. Corrupted memory at 0xffff88807eade00b [ 0xff 0x07 0x00 0x00 0x00 0x00 0x00 0x00 . . . . . . . . ] (in kfence-#110): p9_fcall_fini net/9p/client.c:248 [inline] p9_req_put net/9p/client.c:396 [inline] p9_req_put+0x208/0x250 net/9p/client.c:390 p9_client_walk+0x247/0x540 net/9p/client.c:1165 clone_fid fs/9p/fid.h:21 [inline] v9fs_fid_xattr_set+0xe4/0x2b0 fs/9p/xattr.c:118 v9fs_xattr_set fs/9p/xattr.c:100 [inline] v9fs_xattr_handler_set+0x6f/0x120 fs/9p/xattr.c:159 __vfs_setxattr+0x119/0x180 fs/xattr.c:182 __vfs_setxattr_noperm+0x129/0x5f0 fs/xattr.c:216 __vfs_setxattr_locked+0x1d3/0x260 fs/xattr.c:277 vfs_setxattr+0x143/0x340 fs/xattr.c:309 setxattr+0x146/0x160 fs/xattr.c:617 path_setxattr+0x197/0x1c0 fs/xattr.c:636 __do_sys_setxattr fs/xattr.c:652 [inline] __se_sys_setxattr fs/xattr.c:648 [inline] __ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:648 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 Below is a similar scenario, the scenario in the syzbot log looks more complicated than this one, but this patch can fix it. T21124 p9_read_work ======================== second trans ================================= p9_client_walk p9_client_rpc p9_client_prepare_req p9_tag_alloc req = kmem_cache_alloc(p9_req_cache, GFP_NOFS); tag = idr_alloc << preempted >> req->tc.tag = tag; /* req->[refcount/tag] == uninitialized */ m->rreq = p9_tag_lookup(m->client, m->rc.tag); /* increments uninitalized refcount */ refcount_set(&req->refcount, 2); /* cb drops one ref */ p9_client_cb(req) /* reader thread drops its ref: request is incorrectly freed */ p9_req_put(req) /* use after free and ref underflow */ p9_req_put(req) To fix it, we can initialize the refcount to zero before add to idr.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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

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	728356dedeff8ef999cb436c71333ef4ac51a81c ~ 1cabce56626a61f4f02452cba61ad4332a4b73f8	-
Linux	Linux	4.20	-

II. Public POCs for CVE-2022-50335

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

No public POC found.

III. Intelligence Information for CVE-2022-50335

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https://www.cve.org/CVERecord?id=CVE-2022-50335

Same Patch Batch · Linux · 2025-09-15 · 210 CVEs total

CVE-2022-50235	9.8 CRITICAL	NFSD: Protect against send buffer overflow in NFSv2 READDIR
CVE-2023-53192	9.8 CRITICAL	vxlan: Fix nexthop hash size
CVE-2023-53253	8.8 HIGH	HID: nvidia-shield: Reference hid_device devm allocation of input_dev name
CVE-2023-53226	8.8 HIGH	wifi: mwifiex: Fix OOB and integer underflow when rx packets
CVE-2022-50241	8.8 HIGH	NFSD: fix use-after-free on source server when doing inter-server copy
CVE-2023-53194	8.4 HIGH	fs/ntfs3: Add length check in indx_get_root
CVE-2023-53213	8.1 HIGH	wifi: brcmfmac: slab-out-of-bounds read in brcmf_get_assoc_ies()
CVE-2023-53186	8.1 HIGH	skbuff: Fix a race between coalescing and releasing SKBs
CVE-2023-53254	7.8 HIGH	cacheinfo: Fix shared_cpu_map to handle shared caches at different levels
CVE-2023-53219	7.8 HIGH	media: netup_unidvb: fix use-after-free at del_timer()
CVE-2023-53252	7.8 HIGH	Bluetooth: use RCU for hci_conn_params and iterate safely in hci_sync
CVE-2023-53170	7.8 HIGH	net: dsa: Removed unneeded of_node_put in felix_parse_ports_node
CVE-2023-53176	7.8 HIGH	serial: 8250: Reinit port->pm on port specific driver unbind
CVE-2023-53178	7.8 HIGH	mm: fix zswap writeback race condition
CVE-2023-53179	7.8 HIGH	netfilter: ipset: add the missing IP_SET_HASH_WITH_NET0 macro for ip_set_hash_netportnet.c
CVE-2022-50315	7.8 HIGH	ata: ahci: Match EM_MAX_SLOTS with SATA_PMP_MAX_PORTS
CVE-2023-53184	7.8 HIGH	arm64/sme: Set new vector length before reallocating
CVE-2023-53187	7.8 HIGH	btrfs: fix use-after-free of new block group that became unused
CVE-2025-39800	7.8 HIGH	btrfs: abort transaction on unexpected eb generation at btrfs_copy_root()
CVE-2022-50286	7.8 HIGH	ext4: fix delayed allocation bug in ext4_clu_mapped for bigalloc + inline

Showing top 20 of 210 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux

Same vendor: Linux

V. Comments for CVE-2022-50335

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Goal Reached Thanks to every supporter — we hit 100%!

CVE-2022-50335— 9p: set req refcount to zero to avoid uninitialized usage

Quick assessment

Possible ATT&CK Techniques 3 AI

Affected Version Matrix 12

I. Basic Information for CVE-2022-50335

Vulnerability Information

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Affected Products

II. Public POCs for CVE-2022-50335

III. Intelligence Information for CVE-2022-50335

Same Patch Batch · Linux · 2025-09-15 · 210 CVEs total

IV. Related Vulnerabilities

V. Comments for CVE-2022-50335

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