commit 91ffe5b87187e45a0d58cf0510d773ebe804508d
author Ryan Everett <ryan.everett@arm.com> Tue Jan 23 20:05:42 2024 +0000
committer Ryan Everett <ryan.everett@arm.com> Wed Feb 14 14:19:54 2024 +0000
tree 4ba48817aa6cad97090479684aa46f115d517738
parent 024b395f85162594cc683b1e0d65ae77dfaaafac

Make psa_finish_key_creation thread safe

Hold mutex for the entirety of the call.
We are writing to storage and writing to the slot state here.
If we didn't keep the mutex for the whole duration then we may end up with
another thread seeing that a persistent key is in storage before
our slot is set to FULL; this would be unlinearizable behaviour.

Signed-off-by: Ryan Everett <ryan.everett@arm.com>

library/psa_crypto.c

diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 4a0666b..d53a09d 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1799,6 +1799,11 @@
     (void) slot;
     (void) driver;
 
+#if defined(MBEDTLS_THREADING_C)
+    PSA_THREADING_CHK_RET(mbedtls_mutex_lock(
+                              &mbedtls_threading_key_slot_mutex));
+#endif
+
 #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
     if (!PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) {
 #if defined(MBEDTLS_PSA_CRYPTO_SE_C)
@@ -1838,6 +1843,11 @@
         status = psa_save_se_persistent_data(driver);
         if (status != PSA_SUCCESS) {
             psa_destroy_persistent_key(slot->attr.id);
+
+#if defined(MBEDTLS_THREADING_C)
+            PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
+                                      &mbedtls_threading_key_slot_mutex));
+#endif
             return status;
         }
         status = psa_crypto_stop_transaction();
@@ -1853,6 +1863,10 @@
         }
     }
 
+#if defined(MBEDTLS_THREADING_C)
+    PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
+                              &mbedtls_threading_key_slot_mutex));
+#endif
     return status;
 }