util/mem: fix NULL dereference in nvme_realloc() on allocation failure

If nvme_alloc() fails and returns NULL, the subsequent memcpy() would
dereference a NULL pointer, resulting in undefined behavior. Add a NULL
check on the result of nvme_alloc() and return NULL early, consistent
with standard realloc() semantics where the original pointer remains
valid on failure.

Signed-off-by: Jim Munn <[email protected]>

Author: jimmunn

util/mem.c

@@ -29,6 +29,8 @@ void *nvme_realloc(void *p, size_t len)
 	size_t old_len = malloc_usable_size(p);
 
 	void *result = nvme_alloc(len);
+	if (!result)
+		return NULL;
 
 	if (p) {
 		memcpy(result, p, min(old_len, len));