In the Linux kernel, the following vulnerability has been resolved:
crypto: afalg - Disallow concurrent writes in afalg_sendmsg
Issuing two writes to the same af_alg socket is bogus as the data will be interleaved in an unpredictable fashion. Furthermore, concurrent writes may create inconsistencies in the internal socket state.
Disallow this by adding a new ctx->write field that indiciates exclusive ownership for writing.