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CVE-2021-47632— powerpc/set_memory: Avoid spinlock recursion in change_page_attr()

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change_page_attr函数中的自旋锁递归。

AI Predicted 5.5 Difficulty: Easy EPSS 0.18% · P8

Possible ATT&CK Techniques 1 AI

T1620 · Reflective Code Loading

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 1f9ad21c3b384a8f16d8c46845a48a01d281a603< 6def4eaf0391f24be541633a954c0e4876858b1e affected
1f9ad21c3b384a8f16d8c46845a48a01d281a603< 96917107e67846f1d959ed03be281048efad14c5 affected
1f9ad21c3b384a8f16d8c46845a48a01d281a603< 6ebe5ca2cbe438a688f2ae238ef5a0b0b5f3468a affected
1f9ad21c3b384a8f16d8c46845a48a01d281a603< a4c182ecf33584b9b2d1aa9dad073014a504c01f affected
5.14 affected
< 5.14 unaffected
5.15.34≤ 5.15.* unaffected
5.16.20≤ 5.16.* unaffected
… +2 more rows
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I. Basic Information for CVE-2021-47632

Vulnerability Information
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Vulnerability Title
powerpc/set_memory: Avoid spinlock recursion in change_page_attr()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: powerpc/set_memory: Avoid spinlock recursion in change_page_attr() Commit 1f9ad21c3b38 ("powerpc/mm: Implement set_memory() routines") included a spin_lock() to change_page_attr() in order to safely perform the three step operations. But then commit 9f7853d7609d ("powerpc/mm: Fix set_memory_*() against concurrent accesses") modify it to use pte_update() and do the operation safely against concurrent access. In the meantime, Maxime reported some spinlock recursion. [ 15.351649] BUG: spinlock recursion on CPU#0, kworker/0:2/217 [ 15.357540] lock: init_mm+0x3c/0x420, .magic: dead4ead, .owner: kworker/0:2/217, .owner_cpu: 0 [ 15.366563] CPU: 0 PID: 217 Comm: kworker/0:2 Not tainted 5.15.0+ #523 [ 15.373350] Workqueue: events do_free_init [ 15.377615] Call Trace: [ 15.380232] [e4105ac0] [800946a4] do_raw_spin_lock+0xf8/0x120 (unreliable) [ 15.387340] [e4105ae0] [8001f4ec] change_page_attr+0x40/0x1d4 [ 15.393413] [e4105b10] [801424e0] __apply_to_page_range+0x164/0x310 [ 15.400009] [e4105b60] [80169620] free_pcp_prepare+0x1e4/0x4a0 [ 15.406045] [e4105ba0] [8016c5a0] free_unref_page+0x40/0x2b8 [ 15.411979] [e4105be0] [8018724c] kasan_depopulate_vmalloc_pte+0x6c/0x94 [ 15.418989] [e4105c00] [801424e0] __apply_to_page_range+0x164/0x310 [ 15.425451] [e4105c50] [80187834] kasan_release_vmalloc+0xbc/0x134 [ 15.431898] [e4105c70] [8015f7a8] __purge_vmap_area_lazy+0x4e4/0xdd8 [ 15.438560] [e4105d30] [80160d10] _vm_unmap_aliases.part.0+0x17c/0x24c [ 15.445283] [e4105d60] [801642d0] __vunmap+0x2f0/0x5c8 [ 15.450684] [e4105db0] [800e32d0] do_free_init+0x68/0x94 [ 15.456181] [e4105dd0] [8005d094] process_one_work+0x4bc/0x7b8 [ 15.462283] [e4105e90] [8005d614] worker_thread+0x284/0x6e8 [ 15.468227] [e4105f00] [8006aaec] kthread+0x1f0/0x210 [ 15.473489] [e4105f40] [80017148] ret_from_kernel_thread+0x14/0x1c Remove the read / modify / write sequence to make the operation atomic and remove the spin_lock() in change_page_attr(). To do the operation atomically, we can't use pte modification helpers anymore. Because all platforms have different combination of bits, it is not easy to use those bits directly. But all have the _PAGE_KERNEL_{RO/ROX/RW/RWX} set of flags. All we need it to compare two sets to know which bits are set or cleared. For instance, by comparing _PAGE_KERNEL_ROX and _PAGE_KERNEL_RO you know which bit gets cleared and which bit get set when changing exec permission.
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change_page_attr函数中的自旋锁递归。
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 1f9ad21c3b384a8f16d8c46845a48a01d281a603 ~ 6def4eaf0391f24be541633a954c0e4876858b1e -
Linux Linux 5.14 -

II. Public POCs for CVE-2021-47632

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III. Intelligence Information for CVE-2021-47632

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Patches & Fixes for CVE-2021-47632 (4)

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

CVE-2022-49149 9.8 CRITICAL rxrpc: Fix call timer start racing with call destruction
CVE-2022-49280 9.8 CRITICAL NFSD: prevent underflow in nfssvc_decode_writeargs()
CVE-2022-49093 9.8 CRITICAL skbuff: fix coalescing for page_pool fragment recycling
CVE-2022-49094 9.8 CRITICAL net/tls: fix slab-out-of-bounds bug in decrypt_internal
CVE-2022-49356 9.8 CRITICAL SUNRPC: Trap RDMA segment overflows
CVE-2022-49407 9.8 CRITICAL dlm: fix plock invalid read
CVE-2022-49418 9.8 CRITICAL NFSv4: Fix free of uninitialized nfs4_label on referral lookup.
CVE-2022-49561 9.8 CRITICAL netfilter: conntrack: re-fetch conntrack after insertion
CVE-2022-49362 9.8 CRITICAL NFSD: Fix potential use-after-free in nfsd_file_put()
CVE-2022-49194 9.8 CRITICAL net: bcmgenet: Use stronger register read/writes to assure ordering
CVE-2022-49260 9.8 CRITICAL crypto: hisilicon/sec - fix the aead software fallback for engine
CVE-2022-49201 9.8 CRITICAL ibmvnic: fix race between xmit and reset
CVE-2022-49058 9.1 CRITICAL cifs: potential buffer overflow in handling symlinks
CVE-2022-49328 8.8 HIGH mt76: fix use-after-free by removing a non-RCU wcid pointer
CVE-2022-49238 8.8 HIGH ath11k: free peer for station when disconnect from AP for QCA6390/WCN6855
CVE-2022-49471 8.8 HIGH rtw89: cfo: check mac_id to avoid out-of-bounds
CVE-2022-49159 8.8 HIGH scsi: qla2xxx: Implement ref count for SRB
CVE-2022-49500 8.8 HIGH wl1251: dynamically allocate memory used for DMA
CVE-2022-49479 8.8 HIGH mt76: fix tx status related use-after-free race on station removal
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

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47632

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