CVE-2021-46952 Information

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.

Reference

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