ima: fix buffer overrun in ima_eventdigest_init_common

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ima: fix buffer overrun in ima_eventdigest_init_common Function ima_eventdigest_init() calls ima_eventdigest_init_common() with HASH_ALGO__LAST which is then used to access the array hash_digest_size[] leading to buffer overrun. Have a conditional statement to handle this.

References

• https://git.kernel.org/stable/c/e01aae58e818503f2ffcd34c6f7dc6f90af1057e
• https://git.kernel.org/stable/c/8a84765c62cc0469864e2faee43aae253ad16082
• https://git.kernel.org/stable/c/1ecf0df5205cfb0907eb7984b8671257965a5232
• https://git.kernel.org/stable/c/923168a0631bc42fffd55087b337b1b6c54dcff5