Fix wrong memcpy length for block_interleave == 4 (ggml-org#19575)

Author: Alcpz

ggml/src/ggml-cpu/repack.cpp

@@ -1916,9 +1916,10 @@ static block_q4_Kx8 make_block_q4_Kx8(block_q4_K * in, unsigned int blck_size_in
         int src_offset = (i / 8) * blck_size_interleave;
         int dst_offset = i * blck_size_interleave;
 
+        // buffer large enough for the max interleave block size (8 bytes)
         uint64_t elems;
-        memcpy(&elems, &in[src_id].qs[src_offset], sizeof(uint64_t));
-        memcpy(&out.qs[dst_offset], &elems, sizeof(uint64_t));
+        memcpy(&elems, &in[src_id].qs[src_offset], blck_size_interleave);
+        memcpy(&out.qs[dst_offset], &elems, blck_size_interleave);
     }
 
     // The below logic is designed so as to unpack and rearrange scales and mins values in Q4_K