In the Linux kernel, the following vulnerability has been resolved: KEYS: encrypted: fix integer overflow of datablob_len encrypted_key_al

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

KEYS: encrypted: fix integer overflow of datablob_len

encrypted_key_alloc() stores datablob_len in a u16. It is computed from
multiple string and payload lengths. If the result exceeds U16_MAX, the
assignment truncates the allocation size. KASAN reports a 32760-byte
slab-out-of-bounds write when __ekey_init() copies the master key
description into the undersized buffer.

The total payload length stored in key->datalen is also a u16. Use
check_add_overflow() to reject values that do not fit either destination,
and use kzalloc_flex() for the flexible-array allocation.