CVE-2024-53151

What it actually does

Integer overflow in xdr_check_write_chunk allows user-controlled segcount multiplied by rpcrdma_segment_maxsz * sizeof(*p) to wrap on 32-bit systems, bypassing the xdr_inline_decode buffer size check and enabling subsequent out-of-bounds memory access in the svcrdma receive path.

Why it matters to the business

Organizations running 32-bit Linux kernels that expose NFS/RDMA services face elevated risk of system crashes or potential remote code execution; the low EPSS score indicates limited in-the-wild exploitation so far, but the flaw affects a core kernel networking component used in enterprise storage and high-performance computing environments.

How an attack unfolds

An attacker sends a crafted RPC-over-RDMA message containing an oversized write chunk list; the kernel decodes a large segcount value that overflows the size calculation, causing xdr_inline_decode to accept an invalid buffer length and allowing the attacker to influence subsequent memory operations in the receive context.

How to fix it

Update the Linux kernel to commit 21e1cf688fb0397788c8dd42e1e0b08d58ac5c7b or later; for Ubuntu 16.04 LTS use jq package version 1.5+dfsg-1ubuntu0.1+esm2 or newer; for Ubuntu 14.04 LTS use 1.3-1.1ubuntu1.1+esm3 or newer; disable RDMA transport where not required as a temporary mitigation.

How to confirm the fix worked

Confirm the running kernel contains commit 21e1cf688fb0397788c8dd42e1e0b08d58ac5c7b; verify with 'uname -r' and package manager output that the fixed kernel or jq package is installed; recompile and test with Smatch or similar static analyzers to ensure the overflow check is present.

Typical attack path

1. Establish an RDMA-capable NFS connection to the target
2. Craft an RPC call containing a write chunk header with segcount chosen to trigger 32-bit integer overflow
3. Send the malicious chunk list so that xdr_inline_decode accepts an undersized buffer
4. Trigger out-of-bounds read or write via subsequent RDMA operations or memory accesses
5. Achieve denial of service or attempt code execution depending on memory layout

How to detect it

Inspect kernel logs for warnings or crashes originating from net/sunrpc/xprtrdma/svc_rdma_recvfrom.c around xdr_check_write_chunk; look for unusual segcount values or RDMA receive errors in system logs; correlate with network captures showing malformed RPC-over-RDMA write chunk headers.

What your security team should do

• Prioritize patching 32-bit Linux systems that expose NFS/RDMA services within the next 30 days
• Apply the exact fixed commit or distribution package versions listed above
• Review firewall rules to restrict RDMA traffic to trusted initiators until patches are deployed
• Monitor kernel mailing lists for backports to older stable trees