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

s390/mm: Add NULL pointer check to crst_table_free() base_crst_free()

crst_table_free() used to work with NULL pointers before the conversion
to ptdescs.  Since crst_table_free() can be called with a NULL pointer
(error handling in crst_table_upgrade() add an explicit check.

Also add the same check to base_crst_free() for consistency reasons.

In real life this should not happen, since order two GFP_KERNEL
allocations will not fail, unless FAIL_PAGE_ALLOC is enabled and used.

kernel.org https://git.kernel.org/stable/c/794fa52b94637d6b2e8c9474fbe3983af5c9f046 [No types assigned]

kernel.org https://git.kernel.org/stable/c/b5efb63acf7bddaf20eacfcac654c25c446eabe8 [No types assigned]

kernel.org https://git.kernel.org/stable/c/f80bd8bb6f380bc265834c46058d38b34174813e [No types assigned]