CVE-2021-47107: NFSD: Fix READDIR buffer overflow
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Fix READDIR buffer overflow
If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new initdirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer.
This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly.
With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdrreservespace().
Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2021-47107?
CVE-2021-47107 has been classified as a high severity vulnerability due to the potential for buffer overflow leading to system crashes or arbitrary code execution.
How do I fix CVE-2021-47107?
To fix CVE-2021-47107, update your Linux kernel to a version that includes the patch addressing this vulnerability, specifically versions later than 5.15.12.
What are the affected versions for CVE-2021-47107?
CVE-2021-47107 affects Linux kernel versions from 5.13 up to 5.15.12 and specific release candidates of version 5.16.
What could happen if CVE-2021-47107 is exploited?
If CVE-2021-47107 is exploited, it could lead to a buffer overflow that might allow an attacker to crash the system or execute arbitrary code.
Is CVE-2021-47107 a local or remote vulnerability?
CVE-2021-47107 is considered a remote vulnerability, as it can be triggered by a client sending malicious requests to the server.