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CVE-2021-46990— powerpc/64s: Fix crashes when toggling entry flush barrier

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，该漏洞源于切换入口刷新屏障时可能导致崩溃。

AI Predicted 5.5 Difficulty: Hard EPSS 0.23% · P13

Possible ATT&CK Techniques 1 AI

T1055 · Process Injection

Affected Version Matrix 27

VendorProduct Version RangeStatus
Linux Linux 4a1e90af718d1489ffcecc8f52486c4f5dc0f7a6< 8382b15864e5014261b4f36c2aa89723612ee058 affected
fa4bf9f38184ed7ca4916eb64f8c767d1e279c1f< 0c25a7bb697f2e6ee65b6d63782f675bf129511a affected
db01cad9efe3c3838a6b3a3f68affd295c4b92d6< ee4b7aab93c2631c3bb0753023c5dda592bb666b affected
f69bb4e51f41973fb7594be1479fa689831efe1a< 2db22ba4e0e103f00e0512e0ecce36ac78c644f8 affected
b65458b6be8032c5179d4f562038575d7b3a6be3< 0b4eb172cc12dc102cd0ad013e53ee4463db9508 affected
f79643787e0a0762d2409b7b8334e83f22d85695< d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92 affected
f79643787e0a0762d2409b7b8334e83f22d85695< dd0d6117052faace5440db20fc37175efe921c7d affected
f79643787e0a0762d2409b7b8334e83f22d85695< 5bc00fdda1e934c557351a9c751a205293e68cbf affected
… +19 more rows
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I. Basic Information for CVE-2021-46990

Vulnerability Information
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Vulnerability Title
powerpc/64s: Fix crashes when toggling entry flush barrier
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Fix crashes when toggling entry flush barrier The entry flush mitigation can be enabled/disabled at runtime via a debugfs file (entry_flush), which causes the kernel to patch itself to enable/disable the relevant mitigations. However depending on which mitigation we're using, it may not be safe to do that patching while other CPUs are active. For example the following crash: sleeper[15639]: segfault (11) at c000000000004c20 nip c000000000004c20 lr c000000000004c20 Shows that we returned to userspace with a corrupted LR that points into the kernel, due to executing the partially patched call to the fallback entry flush (ie. we missed the LR restore). Fix it by doing the patching under stop machine. The CPUs that aren't doing the patching will be spinning in the core of the stop machine logic. That is currently sufficient for our purposes, because none of the patching we do is to that code or anywhere in the vicinity.
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，该漏洞源于切换入口刷新屏障时可能导致崩溃。
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 4a1e90af718d1489ffcecc8f52486c4f5dc0f7a6 ~ 8382b15864e5014261b4f36c2aa89723612ee058 -
Linux Linux 5.10 -

II. Public POCs for CVE-2021-46990

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III. Intelligence Information for CVE-2021-46990

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Patches & Fixes for CVE-2021-46990 (1)

Other References for CVE-2021-46990 (6)

Same Patch Batch · Linux · 2024-02-28 · 86 CVEs total

CVE-2021-47013 9.8 CRITICAL net:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send
CVE-2021-47036 9.8 CRITICAL udp: skip L4 aggregation for UDP tunnel packets
CVE-2021-46999 9.8 CRITICAL sctp: do asoc update earlier in sctp_sf_do_dupcook_a
CVE-2021-47035 8.8 HIGH iommu/vt-d: Remove WO permissions on second-level paging entries
CVE-2021-47017 8.8 HIGH ath10k: Fix a use after free in ath10k_htc_send_bundle
CVE-2021-47049 8.4 HIGH Drivers: hv: vmbus: Use after free in __vmbus_open()
CVE-2021-47014 7.8 HIGH net/sched: act_ct: fix wild memory access when clearing fragments
CVE-2020-36785 7.8 HIGH media: atomisp: Fix use after free in atomisp_alloc_css_stat_bufs()
CVE-2021-47040 7.8 HIGH io_uring: fix overflows checks in provide buffers
CVE-2021-47048 7.8 HIGH spi: spi-zynqmp-gqspi: fix use-after-free in zynqmp_qspi_exec_op
CVE-2021-46984 7.8 HIGH kyber: fix out of bounds access when preempted
CVE-2021-46993 7.8 HIGH sched: Fix out-of-bound access in uclamp
CVE-2021-46998 7.8 HIGH ethernet:enic: Fix a use after free bug in enic_hard_start_xmit
CVE-2021-46992 7.8 HIGH netfilter: nftables: avoid overflows in nft_hash_buckets()
CVE-2021-46977 7.8 HIGH KVM: VMX: Disable preemption when probing user return MSRs
CVE-2021-47012 7.8 HIGH RDMA/siw: Fix a use after free in siw_alloc_mr
CVE-2021-47011 7.8 HIGH mm: memcontrol: slab: fix obtain a reference to a freeing memcg
CVE-2020-36787 7.8 HIGH media: aspeed: fix clock handling logic
CVE-2021-47041 7.5 HIGH nvmet-tcp: fix incorrect locking in state_change sk callback
CVE-2021-46983 7.5 HIGH nvmet-rdma: Fix NULL deref when SEND is completed with error

Showing top 20 of 86 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-46990

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