CVE-2021-47107

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description The issue is related to a buffer overflow in the NFSD component of the Linux kernel. If a client sends a READDIR count argument that is too small, the buffer size calculation results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect, and NFSD has never checked the READDIR count argument. The problem was exposed when entry encoding changed, affecting the pointer arithmetic in xdr reserve space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request, and there are no unit tests that exercise the behavior of READDIR at the lower bound of @count values.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.