what you don't know can hurt you
Showing 1 - 2 of 2 RSS Feed

CVE-2021-29657

Status Candidate

Overview

arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.

Related Files

KVM nested_svm_vmrun Double Fetch
Posted Jun 30, 2021
Authored by Google Security Research, Felix Wilhelm

A KVM guest on AMD can launch a L2 guest without the Intercept VMRUN control bit by exploiting a TOCTOU vulnerability in nested_svm_vmrun. Executing vmrun from the L2 guest, will then trigger a second call to nested_svm_vmrun and corrupt svm->nested.hsave with data copied out of the L2 vmcb. For kernel versions that include the commit "2fcf4876: KVM: nSVM: implement on demand allocation of the nested state" (>=5.10), the guest can free the MSR permission bit in svm->nested.msrpm, while it's still in use and gain unrestricted access to host MSRs.

tags | exploit, kernel
advisories | CVE-2021-29657
MD5 | 814987fd3e7902c83f77c7f4aa4a3585
Ubuntu Security Notice USN-4948-1
Posted May 12, 2021
Authored by Ubuntu | Site security.ubuntu.com

Ubuntu Security Notice 4948-1 - Ryota Shiga discovered that the eBPF implementation in the Linux kernel did not properly verify that a BPF program only reserved as much memory for a ring buffer as was allocated. A local attacker could use this to cause a denial of service or execute arbitrary code. Manfred Paul discovered that the eBPF implementation in the Linux kernel did not properly track bounds on bitwise operations. A local attacker could use this to cause a denial of service or execute arbitrary code. Various other issues were also addressed.

tags | advisory, denial of service, arbitrary, kernel, local
systems | linux, ubuntu
advisories | CVE-2020-25670, CVE-2021-28688, CVE-2021-28951, CVE-2021-28952, CVE-2021-28964, CVE-2021-28971, CVE-2021-28972, CVE-2021-29264, CVE-2021-29266, CVE-2021-29646, CVE-2021-29647, CVE-2021-29649, CVE-2021-29650, CVE-2021-29657, CVE-2021-31916, CVE-2021-3483, CVE-2021-3489, CVE-2021-3490, CVE-2021-3491
MD5 | 151d9671a4c69f74d2e7803115cefc7b
Page 1 of 1
Back1Next

File Archive:

January 2022

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Jan 1st
    2 Files
  • 2
    Jan 2nd
    0 Files
  • 3
    Jan 3rd
    20 Files
  • 4
    Jan 4th
    4 Files
  • 5
    Jan 5th
    37 Files
  • 6
    Jan 6th
    20 Files
  • 7
    Jan 7th
    4 Files
  • 8
    Jan 8th
    0 Files
  • 9
    Jan 9th
    0 Files
  • 10
    Jan 10th
    18 Files
  • 11
    Jan 11th
    8 Files
  • 12
    Jan 12th
    19 Files
  • 13
    Jan 13th
    31 Files
  • 14
    Jan 14th
    2 Files
  • 15
    Jan 15th
    2 Files
  • 16
    Jan 16th
    2 Files
  • 17
    Jan 17th
    18 Files
  • 18
    Jan 18th
    13 Files
  • 19
    Jan 19th
    15 Files
  • 20
    Jan 20th
    29 Files
  • 21
    Jan 21st
    12 Files
  • 22
    Jan 22nd
    0 Files
  • 23
    Jan 23rd
    0 Files
  • 24
    Jan 24th
    0 Files
  • 25
    Jan 25th
    0 Files
  • 26
    Jan 26th
    0 Files
  • 27
    Jan 27th
    0 Files
  • 28
    Jan 28th
    0 Files
  • 29
    Jan 29th
    0 Files
  • 30
    Jan 30th
    0 Files
  • 31
    Jan 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2020 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close