CyberSecBulletin
CVE-2022-50093NVD status: Analyzed

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2022-50093 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions b12304984654d8e58a2b22ff94c4410906d6267f, 5659efdadf04b56707d58c1b758df16d2e0eff2c, 0b4c0003aeda32a600f95df53b2848da8a5aa3fa as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to b12304984654d8e58a2b22ff94c4410906d6267f or 5659efdadf04b56707d58c1b758df16d2e0eff2c or 0b4c0003aeda32a600f95df53b2848da8a5aa3fa or 73ce2046e04ad488cecc66757c36cbe1bdf089d4, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.4.211 or 5.10.137 or 5.15.61 or 5.18.18, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxee34b32d8c2950f66038c8975747ef9aec855289 up to, but not including, b12304984654d8e58a2b22ff94c4410906d6267f; ee34b32d8c2950f66038c8975747ef9aec855289 up to, but not including, 5659efdadf04b56707d58c1b758df16d2e0eff2c; ee34b32d8c2950f66038c8975747ef9aec855289 up to, but not including, 0b4c0003aeda32a600f95df53b2848da8a5aa3fa; ee34b32d8c2950f66038c8975747ef9aec855289 up to, but not including, 73ce2046e04ad488cecc66757c36cbe1bdf089d4; ee34b32d8c2950f66038c8975747ef9aec855289 up to, but not including, c2304c50f4d94f56c2e326f25c9dc8cf2ba6f5fa; ee34b32d8c2950f66038c8975747ef9aec855289 up to, but not including, b0b0b77ea611e3088e9523e60860f4f41b62b235; 2.6.33b12304984654d8e58a2b22ff94c4410906d6267f, 5659efdadf04b56707d58c1b758df16d2e0eff2c, 0b4c0003aeda32a600f95df53b2848da8a5aa3fa, 73ce2046e04ad488cecc66757c36cbe1bdf089d4, c2304c50f4d94f56c2e326f25c9dc8cf2ba6f5fa, b0b0b77ea611e3088e9523e60860f4f41b62b235
LinuxLinux Kernel2.6.33 up to, but not including, 5.4.211; 5.5 up to, but not including, 5.10.137; 5.11 up to, but not including, 5.15.61; 5.16 up to, but not including, 5.18.18; 5.19 up to, but not including, 5.19.25.4.211, 5.10.137, 5.15.61, 5.18.18, 5.19.2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.

Official description

In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: avoid invalid memory access via node_online(NUMA_NO_NODE) KASAN reports: [ 4.668325][ T0] BUG: KASAN: wild-memory-access in dmar_parse_one_rhsa (arch/x86/include/asm/bitops.h:214 arch/x86/include/asm/bitops.h:226 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/nodemask.h:415 drivers/iommu/intel/dmar.c:497) [ 4.676149][ T0] Read of size 8 at addr 1fffffff85115558 by task swapper/0/0 [ 4.683454][ T0] [ 4.685638][ T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc3-00004-g0e862838f290 #1 [ 4.694331][ T0] Hardware name: Supermicro SYS-5018D-FN4T/X10SDV-8C-TLN4F, BIOS 1.1 03/02/2016 [ 4.703196][ T0] Call Trace: [ 4.706334][ T0] <TASK> [ 4.709133][ T0] ? dmar_parse_one_rhsa (arch/x86/include/asm/bitops.h:214 arch/x86/include/asm/bitops.h:226 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/nodemask.h:415 drivers/iommu/intel/dmar.c:497) after converting the type of the first argument (@nr, bit number) of arch_test_bit() from `long` to `unsigned long`[0]. Under certain conditions (for example, when ACPI NUMA is disabled via command line), pxm_to_node() can return %NUMA_NO_NODE (-1). It is valid 'magic' number of NUMA node, but not valid bit number to use in bitops. node_online() eventually descends to test_bit() without checking for the input, assuming it's on caller side (which might be good for perf-critical tasks). There, -1 becomes %ULONG_MAX which leads to an insane array index when calculating bit position in memory. For now, add an explicit check for @node being not %NUMA_NO_NODE before calling test_bit(). The actual logics didn't change here at all. [0] https://github.com/norov/linux/commit/0e862838f290147ea9c16db852d8d494b552d38d

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that provides appropriate memory abstractions.

More Out-of-bounds Read vulnerabilities (CWE-125)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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