CWE-362 使用共享资源的并发执行不恰当同步问题(竞争条件) 类漏洞列表 693

$transfer_amount = GetTransferAmount(); $balance = GetBalanceFromDatabase(); if ($transfer_amount < 0) { FatalError("Bad Transfer Amount"); } $newbalance = $balance - $transfer_amount; if (($balance - $transfer_amount) < 0) { FatalError("Insufficient Funds"); } SendNewBalanceToDatabase($newbalance); NotifyUser("Transfer of $transfer_amount succeeded."); NotifyUser("New balance: $newbalance");

In the following pseudocode, the attacker makes two simultaneous calls of the program, CALLER-1 and CALLER-2. Both callers are for the same user account. CALLER-1 (the attacker) is associated with PROGRAM-1 (the instance that handles CALLER-1). CALLER-2 is associated with PROGRAM-2. CALLER-1 makes a transfer request of 80.00. PROGRAM-1 calls GetBalanceFromDatabase and sets $balance to 100.00 PROGRAM-1 calculates $newbalance as 20.00, then calls SendNewBalanceToDatabase(). Due to high server load, the PROGRAM-1 call to SendNewBalanceToDatabase() encounters a delay. CALLER-2 makes a transfer req

void f(pthread_mutex_t *mutex) { pthread_mutex_lock(mutex); /* access shared resource */ pthread_mutex_unlock(mutex); }

int f(pthread_mutex_t *mutex) { int result; result = pthread_mutex_lock(mutex); if (0 != result) return result; /* access shared resource */ return pthread_mutex_unlock(mutex); }