CVE-2021-46952: linux kernel Out-of-bounds Read — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds Fix shift out-of-bounds in xprt_calc_majortimeo(). This is caused by a garbage timeout (retrans) mount option being passed to nfs mount, in this case from syzkaller. If the protocol is XPRT_TRANSPORT_UDP, then 'retrans' is a shift value for a 64-bit long integer, so 'retrans' cannot be >= 64. If it is >= 64, fail the mount and return an error.

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CVSS v3.1 Score

7.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.6.0 — 5.10.36
linux	linux_kernel	5.11.0 — 5.11.20
linux	linux_kernel	5.12.0 — 5.12.3

References

Advisories & Patches

https://git.kernel.org/stable/c/2f3380121d49e829fb73ba86240c181bc32ad897 https://git.kernel.org/stable/c/3d0163821c035040a46d816a42c0780f0f0a30a8 https://git.kernel.org/stable/c/96fa26b74cdcf9f5c98996bf36bec9fb5b19ffe2 https://git.kernel.org/stable/c/c09f11ef35955785f92369e25819bf0629df2e59 https://git.kernel.org/stable/c/2f3380121d49e829fb73ba86240c181bc32ad897 https://git.kernel.org/stable/c/3d0163821c035040a46d816a42c0780f0f0a30a8 https://git.kernel.org/stable/c/96fa26b74cdcf9f5c98996bf36bec9fb5b19ffe2 https://git.kernel.org/stable/c/c09f11ef35955785f92369e25819bf0629df2e59

Frequently Asked Questions

What is CVE-2021-46952? +

In the Linux kernel, the following vulnerability has been resolved: NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds Fix shift out-of-bounds in xprt_calc_majortimeo(). This is caused by a garbage timeout (retrans) mount option being passed to nfs mount, in this case from syzkaller. If the protocol is XPRT_TRANSPORT_UDP, then 'retrans' is a shift value for a 64-bit long integer, so 'retrans' cannot be >= 64. If it is >= 64, fail the mount and return an error. It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2021-46952? +

CVE-2021-46952 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2021-46952? +

CVE-2021-46952 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2021-46952? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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