Bug 1365856 - fix double-checked-locking in secoid, r=ttaubert

Differential Revision: https://nss-review.dev.mozaws.net/D376

--HG--
extra : rebase_source : d9a50edb534ea5e421b63129340cc1daa8180f86
extra : amend_source : 8c5ccfebbeec41a4eb0b0f3402c94b7e7eb4bb57

lib/util/secoid.c

@@ -1841,13 +1841,11 @@ secoid_FindDynamic(const SECItem *key)
 {
     SECOidData *ret = NULL;
 
+    NSSRWLock_LockRead(dynOidLock);
     if (dynOidHash) {
-        NSSRWLock_LockRead(dynOidLock);
-        if (dynOidHash) { /* must check it again with lock held. */
-            ret = (SECOidData *)PL_HashTableLookup(dynOidHash, key);
-        }
-        NSSRWLock_UnlockRead(dynOidLock);
+        ret = (SECOidData *)PL_HashTableLookup(dynOidHash, key);
     }
+    NSSRWLock_UnlockRead(dynOidLock);
     if (ret == NULL) {
         PORT_SetError(SEC_ERROR_UNRECOGNIZED_OID);
     }
@@ -1866,14 +1864,12 @@ secoid_FindDynamicByTag(SECOidTag tagnum)
     }
     tagNumDiff = tagnum - SEC_OID_TOTAL;
 
-    if (dynOidTable) {
-        NSSRWLock_LockRead(dynOidLock);
-        if (dynOidTable != NULL && /* must check it again with lock held. */
-            tagNumDiff < dynOidEntriesUsed) {
-            dxo = dynOidTable[tagNumDiff];
-        }
-        NSSRWLock_UnlockRead(dynOidLock);
+    NSSRWLock_LockRead(dynOidLock);
+    if (dynOidTable != NULL &&
+        tagNumDiff < dynOidEntriesUsed) {
+        dxo = dynOidTable[tagNumDiff];
     }
+    NSSRWLock_UnlockRead(dynOidLock);
     if (dxo == NULL) {
         PORT_SetError(SEC_ERROR_UNRECOGNIZED_OID);
     }