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

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2021-47277— kvm: avoid speculation-based attacks from out-of-range memslot accesses

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，该漏洞源于访客可以以 gfn 无效的方式访问无效的物理地址。

AI Predicted 7.5 Difficulty: Hard EPSS 0.26% · P17

Possible ATT&CK Techniques 1 AI

T1570 · Lateral Tool Transfer

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 8a7ae055f3533b520401c170ac55e30628b34df5< 3098b86390a6b9ea52657689f08410baf130ceff affected
8a7ae055f3533b520401c170ac55e30628b34df5< 740621309b25bbf619b8a0ba5fd50a8e58989441 affected
8a7ae055f3533b520401c170ac55e30628b34df5< 361ce3b917aff93123e9e966d8608655c967f438 affected
8a7ae055f3533b520401c170ac55e30628b34df5< 22b87fb17a28d37331bb9c1110737627b17f6781 affected
8a7ae055f3533b520401c170ac55e30628b34df5< bff1fbf0cf0712686f1df59a83fba6e31d2746a0 affected
8a7ae055f3533b520401c170ac55e30628b34df5< 7af299b97734c7e7f465b42a2139ce4d77246975 affected
8a7ae055f3533b520401c170ac55e30628b34df5< ed0e2a893092c7fcb4ff7ba74e5efce53a6f5940 affected
8a7ae055f3533b520401c170ac55e30628b34df5< da27a83fd6cc7780fea190e1f5c19e87019da65c affected
… +10 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2021-47277

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
kvm: avoid speculation-based attacks from out-of-range memslot accesses
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: kvm: avoid speculation-based attacks from out-of-range memslot accesses KVM's mechanism for accessing guest memory translates a guest physical address (gpa) to a host virtual address using the right-shifted gpa (also known as gfn) and a struct kvm_memory_slot. The translation is performed in __gfn_to_hva_memslot using the following formula: hva = slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE It is expected that gfn falls within the boundaries of the guest's physical memory. However, a guest can access invalid physical addresses in such a way that the gfn is invalid. __gfn_to_hva_memslot is called from kvm_vcpu_gfn_to_hva_prot, which first retrieves a memslot through __gfn_to_memslot. While __gfn_to_memslot does check that the gfn falls within the boundaries of the guest's physical memory or not, a CPU can speculate the result of the check and continue execution speculatively using an illegal gfn. The speculation can result in calculating an out-of-bounds hva. If the resulting host virtual address is used to load another guest physical address, this is effectively a Spectre gadget consisting of two consecutive reads, the second of which is data dependent on the first. Right now it's not clear if there are any cases in which this is exploitable. One interesting case was reported by the original author of this patch, and involves visiting guest page tables on x86. Right now these are not vulnerable because the hva read goes through get_user(), which contains an LFENCE speculation barrier. However, there are patches in progress for x86 uaccess.h to mask kernel addresses instead of using LFENCE; once these land, a guest could use speculation to read from the VMM's ring 3 address space. Other architectures such as ARM already use the address masking method, and would be susceptible to this same kind of data-dependent access gadgets. Therefore, this patch proactively protects from these attacks by masking out-of-bounds gfns in __gfn_to_hva_memslot, which blocks speculation of invalid hvas. Sean Christopherson noted that this patch does not cover kvm_read_guest_offset_cached. This however is limited to a few bytes past the end of the cache, and therefore it is unlikely to be useful in the context of building a chain of data dependent accesses.
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，该漏洞源于访客可以以 gfn 无效的方式访问无效的物理地址。
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 8a7ae055f3533b520401c170ac55e30628b34df5 ~ 3098b86390a6b9ea52657689f08410baf130ceff -
Linux Linux 2.6.25 -

II. Public POCs for CVE-2021-47277

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2021-47277

请登录查看更多情报信息。

Other References for CVE-2021-47277 (8)

Same Patch Batch · Linux · 2024-05-21 · 361 CVEs total

CVE-2023-52741 9.8 CRITICAL cifs: Fix use-after-free in rdata->read_into_pages()
CVE-2021-47378 9.8 CRITICAL nvme-rdma: destroy cm id before destroy qp to avoid use after free
CVE-2023-52755 9.8 CRITICAL ksmbd: fix slab out of bounds write in smb_inherit_dacl()
CVE-2021-47427 9.8 CRITICAL scsi: iscsi: Fix iscsi_task use after free
CVE-2023-52732 9.8 CRITICAL ceph: blocklist the kclient when receiving corrupted snap trace
CVE-2021-47328 9.8 CRITICAL scsi: iscsi: Fix conn use after free during resets
CVE-2021-47232 9.8 CRITICAL can: j1939: fix Use-after-Free, hold skb ref while in use
CVE-2023-52846 8.8 HIGH hsr: Prevent use after free in prp_create_tagged_frame()
CVE-2023-52769 8.8 HIGH wifi: ath12k: fix htt mlo-offset event locking
CVE-2023-52790 8.8 HIGH swiotlb: fix out-of-bounds TLB allocations with CONFIG_SWIOTLB_DYNAMIC
CVE-2021-47308 8.8 HIGH scsi: libfc: Fix array index out of bound exception
CVE-2021-47390 8.8 HIGH KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect()
CVE-2023-52801 8.8 HIGH iommufd: Fix missing update of domains_itree after splitting iopt_area
CVE-2023-52776 8.8 HIGH wifi: ath12k: fix dfs-radar and temperature event locking
CVE-2023-52798 8.8 HIGH wifi: ath11k: fix dfs radar event locking
CVE-2021-47388 8.8 HIGH mac80211: fix use-after-free in CCMP/GCMP RX
CVE-2023-52829 8.4 HIGH wifi: ath12k: fix possible out-of-bound write in ath12k_wmi_ext_hal_reg_caps()
CVE-2021-47240 8.4 HIGH net: qrtr: fix OOB Read in qrtr_endpoint_post
CVE-2021-47352 8.4 HIGH virtio-net: Add validation for used length
CVE-2021-47244 8.2 HIGH mptcp: Fix out of bounds when parsing TCP options

Showing top 20 of 361 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47277

No comments yet

Leave a comment