CBMC does not recognize pointer initializations outside functions

[AmPaschal]

We observed that CBMC does not recognize pointers that are initialized within a C file but outside a function.
It marks these pointers as INVALID-X where X is an integer.

For example, in the code below

#define PACKETBUF_SIZE 128

static uint32_t packetbuf_aligned[(PACKETBUF_SIZE + 3) / 4];
// Initializing a pointer outside a function causes CBMC to misbehave
uint8_t *packetbuf = (uint8_t *)packetbuf_aligned;

void harness() {

    uint16_t channelId;
    uint8_t *data = packetbuf;

    memcpy(&channelId, data, 2);
    
}

packetbuf is initialized to point to the statically allocated packetbuf_aligned array.
However, when data is defined to point to packetbuf, CBMC sees the packetbuf pointer as invalid and subsequently, makes data invalid.
As a result, an error is reported in the memcpy line where data is accessed.

We tested this with CBMC v6.3.1