found bug in dm_distributed_keys_get

[tiamo]

dm_distributed_keys_get returns address of local variable 'peer_enc_key';

sdk version: nRF51_SDK_9.0.0_2e23562

in function ret_code_t dm_distributed_keys_get(dm_handle_t const * p_handle, dm_sec_keyset_t * p_key_dist)

peer_enc_key declared at [device_manager_peripheral.c:2418, device_manager_central.c:2386] as ble_gap_enc_key_t peer_enc_key;

and used at [device_manager_peripheral.c:2427, device_manager_peripheral.c:2450, device_manager_central.c:2413]

p_key_dist->keys_periph.enc_key.p_enc_key = (dm_enc_key_t *)&peer_enc_key;

[Susheel Nuguru]

can you please explain this bug in more detail. What is wrong with peer_enc_key?

[tiamo]

in c language, local variables are allocated on stack area, after the function returns to its caller, the stack area will be 'destroyed', so the memory of the local variables becomes invalid, actually, it will be overwritten if you call another function.

[Susheel Nuguru]

True , it is a bug. I think that inside the definition of dm_sec_keyset_t, the declaration of of p_enc_key should not be a pointer but instead a full variable like this

union 
{
    dm_enc_key_t       p_enc_key;  /**< Pointer to Device Manager encryption information structure. */
} enc_key;

Then we can read the memory directly into into like this

   err_code = pstorage_load((uint8_t *)& p_key_dist->keys_periph.enc_key.p_enc_key,
                             &block_handle,
                             BOND_SIZE,
                             BOND_STORAGE_OFFSET);

[Susheel Nuguru]

This has not been fixed in SDK10.0