mm/vma: correctly unaccount on mmap_prepare() failure

In the Linux kernel, the following vulnerability has been resolved: mm/vma: correctly unaccount on mmap_prepare() failure __mmap_setup() accounts memory for relevant mappings via: security_vm_enough_memory_mm() -> __vm_enough_memory() -> vm_acct_memory() If __mmap_setup() fails, this indicates that this accounting did not take place, and thus it's appropriate for __mmap_region() to jump to abort_munmap. However if call_mmap_prepare() fails, it also jumps there and any accounted memory is not correctly unaccounted. Fix this by handling each error separately.

Where it's fixed