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In all Qualcomm products with Android releases from CAF using the Linux kernel, a race condition exists in an IOCTL handler potentially leading to an integer overflow and then an out-of-bounds write.
In all Qualcomm products with Android releases from CAF using the Linux kernel, a race condition exists in an IOCTL handler potentially leading to an integer overflow and then an out-of-bounds write.
CVSS 3.0 Base Score 7. CVSS Attack Vector: local. CVSS Attack Complexity: high. CVSS Vector: (CVSS:3.0/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H).
CVSS 2.0 Base Score 7.6. CVSS Attack Vector: network. CVSS Attack Complexity: high. CVSS Vector: (AV:N/AC:H/Au:N/C:C/I:C/A:C).
The following image processing code allocates a table for images.
...This code intends to allocate a table of size num_imgs, however as num_imgs grows large, the calculation determining the size of the list will eventually overflow (CWE-190). This will result in a very small list to be allocated instead. If the subsequent code operates on the list as if it were num_imgs long, it may result in many types of out-of-bounds problems (CWE-119).
The following code excerpt from OpenSSH 3.3 demonstrates a classic case of integer overflow:
}for (i = 0; i < nresp; i++) response[i] = packet_get_string(NULL);If nresp has the value 1073741824 and sizeof(char*) has its typical value of 4, then the result of the operation nresp*sizeof(char*) overflows, and the argument to xmalloc() will be 0. Most malloc() implementations will happily allocate a 0-byte buffer, causing the subsequent loop iterations to overflow the heap buffer response.
Integer overflows can be complicated and difficult to detect. The following example is an attempt to show how an integer overflow may lead to undefined looping behavior:
}bytesRec += getFromInput(buf+bytesRec);In the above case, it is entirely possible that bytesRec may overflow, continuously creating a lower number than MAXGET and also overwriting the first MAXGET-1 bytes of buf.
In this example the method determineFirstQuarterRevenue is used to determine the first quarter revenue for an accounting/business application. The method retrieves the monthly sales totals for the first three months of the year, calculates the first quarter sales totals from the monthly sales totals, calculates the first quarter revenue based on the first quarter sales, and finally saves the first quarter revenue results to the database.
}
return 0;// Variable for sales revenue for the quarter// Calculate quarterly total// Calculate the total revenue for the quarterHowever, in this example the primitive type short int is used for both the monthly and the quarterly sales variables. In C the short int primitive type has a maximum value of 32768. This creates a potential integer overflow if the value for the three monthly sales adds up to more than the maximum value for the short int primitive type. An integer overflow can lead to data corruption, unexpected behavior, infinite loops and system crashes. To correct the situation the appropriate primitive type should be used, as in the example below, and/or provide some validation mechanism to ensure that the maximum value for the primitive type is not exceeded.
}
...// Calculate quarterly total// Calculate the total revenue for the quarterNote that an integer overflow could also occur if the quarterSold variable has a primitive type long but the method calculateRevenueForQuarter has a parameter of type short.
This code could be used in an e-commerce application that supports transfers between accounts. It takes the total amount of the transfer, sends it to the new account, and deducts the amount from the original account.
NotifyUser("New balance: $newbalance");FatalError("Bad Transfer Amount");FatalError("Insufficient Funds");A race condition could occur between the calls to GetBalanceFromDatabase() and SendNewBalanceToDatabase().
Suppose the balance is initially 100.00. An attack could be constructed as follows:
PROGRAM-2 sends a request to update the database, setting the balance to 99.00At this stage, the attacker should have a balance of 19.00 (due to 81.00 worth of transfers), but the balance is 99.00, as recorded in the database.
To prevent this weakness, the programmer has several options, including using a lock to prevent multiple simultaneous requests to the web application, or using a synchronization mechanism that includes all the code between GetBalanceFromDatabase() and SendNewBalanceToDatabase().
The following function attempts to acquire a lock in order to perform operations on a shared resource.
}
pthread_mutex_unlock(mutex);/* access shared resource */However, the code does not check the value returned by pthread_mutex_lock() for errors. If pthread_mutex_lock() cannot acquire the mutex for any reason, the function may introduce a race condition into the program and result in undefined behavior.
In order to avoid data races, correctly written programs must check the result of thread synchronization functions and appropriately handle all errors, either by attempting to recover from them or reporting it to higher levels.
}
return pthread_mutex_unlock(mutex);return result;/* access shared resource */Suppose a processor's Memory Management Unit (MMU) has 5 other shadow MMUs to distribute its workload for its various cores. Each MMU has the start address and end address of "accessible" memory. Any time this accessible range changes (as per the processor's boot status), the main MMU sends an update message to all the shadow MMUs.
Suppose the interconnect fabric does not prioritize such "update" packets over other general traffic packets. This introduces a race condition. If an attacker can flood the target with enough messages so that some of those attack packets reach the target before the new access ranges gets updated, then the attacker can leverage this scenario.
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