The Salsa20 encryption algorithm in the Linux kernel, before 4.14.8, does not correctly handle zero-length inputs. This allows a local attacker the ability to use the AF_ALG-based skcipher interface to cause a denial of service (uninitialized-memory free and kernel crash) or have an unspecified other impact by executing a crafted sequence of system calls that use the blkcipher_walk API. Both the generic implementation (crypto/salsa20_generic.c) and x86 implementation (arch/x86/crypto/salsa20_glue.c) of Salsa20 are vulnerable.