ANDROID: KVM: arm64: Fix hyp_alloc() upper size check

The maximum size is of an allocation is bound to the u32 type of alloc
in struct chunk_hdr.

Bug: 431949921
Bug: 357781595
Reported-by: Hiroyuki Katsura <hk590@cam.ac.uk>
Change-Id: Ifedf1e778afd9c728b654ac223f5f725edc65034
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

arch/arm64/kvm/hyp/nvhe/alloc.c

@@ -552,6 +552,12 @@ void *hyp_alloc(size_t size)
 	size_t missing_map;
 	int ret = 0;
 
+	/* constrained by chunk_hdr *_size types */
+	if (size > U32_MAX) {
+		ret = -E2BIG;
+		goto end_unlocked;
+	}
+
 	size = ALIGN(size ?: MIN_ALLOC, MIN_ALLOC);
 
 	hyp_spin_lock(&allocator->lock);
@@ -587,9 +593,11 @@ void *hyp_alloc(size_t size)
 	}
 
 	WARN_ON(chunk_install(chunk, size, last_chunk, allocator));
+
 end:
 	hyp_spin_unlock(&allocator->lock);
 
+end_unlocked:
 	*(this_cpu_ptr(&hyp_allocator_errno)) = ret;
 
 	/* Enforce zeroing allocated memory */