CVE-2023-53817

In the Linux kernel, the following vulnerability has been resolved:

crypto: lib/mpi - avoid null pointer deref in mpi_cmp_ui()

During NVMeTCP Authentication a controller can trigger a kernel oops by specifying the 8192 bit Diffie Hellman group and passing a correctly sized, but zeroed Diffie Hellamn value. mpi_cmp_ui() was detecting this if the second parameter was 0, but 1 is passed from dh_is_pubkey_valid(). This causes the null pointer u->d to be dereferenced towards the end of mpi_cmp_ui()

This vulnerability presents a denial of service risk under upstream configurations where a remote storage controller initiates an authentication exchange using malformed cryptographic parameters. The issue stems from improper handling of zeroed Diffie-Hellman public keys within the multiprecision integer library, which can result in a kernel crash. Supported Red Hat Enterprise Linux releases are not affected, as the vulnerable implementation is not present in our kernel builds.