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Fix potential bug in psa_destroy_key where multiple threads can return PSA_SUCCESS

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Threads lose the mutex between locking the slot and changing the slot's state.
Make it so that threads check if another thread has completed a destruction during this period.
Also fix the issue with the incorrect status variable being used.

Signed-off-by: Ryan Everett <ryan.everett@arm.com>
This commit is contained in:
Ryan Everett 2024-03-08 18:35:09 +00:00
parent 080a5171e2
commit d868b746a8
1 changed files with 14 additions and 3 deletions
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17
library/psa_crypto.c
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@ -1106,6 +1106,17 @@ psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key)
* fully destroyed. */
PSA_THREADING_CHK_GOTO_EXIT(mbedtls_mutex_lock(
&mbedtls_threading_key_slot_mutex));
if (slot->state == PSA_SLOT_PENDING_DELETION) {
/* Another thread has destroyed the key between us locking the slot
* and us gaining the mutex. Unregister from the slot,
* and report that the key does not exist. */
status = psa_unregister_read(slot);
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
return (status == PSA_SUCCESS) ? PSA_ERROR_INVALID_HANDLE : status;
}
#endif
/* Set the key slot containing the key description's state to
* PENDING_DELETION. This stops new operations from registering
@ -1115,10 +1126,10 @@ psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key)
* If the key is persistent, we can now delete the copy of the key
* from memory. If the key is opaque, we require the driver to
* deal with the deletion. */
status = psa_key_slot_state_transition(slot, PSA_SLOT_FULL,
PSA_SLOT_PENDING_DELETION);
overall_status = psa_key_slot_state_transition(slot, PSA_SLOT_FULL,
PSA_SLOT_PENDING_DELETION);
if (status != PSA_SUCCESS) {
if (overall_status != PSA_SUCCESS) {
goto exit;
}