Signed integer overflow in the bttv_read function in the bttv driver (bttv-driver.c) in Linux kernel before 2.4.20 has unknown impact and attack vectors.
A critical integer overflow vulnerability exists in the bttv driver of older Linux kernels, potentially allowing an attacker to execute arbitrary code with kernel privileges. This vulnerability, stemming from a flaw in how the driver handles video data, could lead to a complete system compromise, including data theft and denial of service.
Step 1: Driver Interaction: The attacker interacts with the bttv device driver, typically through a read() system call. This interaction involves specifying parameters such as the offset and size of the data to be read from the video buffer.
Step 2: Input Manipulation: The attacker crafts malicious input values for the offset and size parameters. These values are specifically designed to cause an integer overflow within the bttv_read function.
Step 3: Integer Overflow: The bttv_read function performs calculations using the attacker-supplied offset and size values. Due to the crafted input, these calculations result in a signed integer overflow.
Step 4: Memory Corruption: The overflowed integer is used in subsequent memory operations, such as calculating buffer addresses or sizes. This leads to memory corruption, potentially allowing the attacker to write to arbitrary memory locations or read beyond buffer boundaries.
Step 5: Code Execution/Privilege Escalation: The memory corruption can be exploited to overwrite critical kernel data structures, such as function pointers or control data. This allows the attacker to redirect program execution to a malicious code, achieving arbitrary code execution with kernel privileges. This can be used to escalate privileges, install rootkits, or gain complete control of the system.
The vulnerability lies within the bttv_read function of the bttv driver (bttv-driver.c) in Linux kernel versions prior to 2.4.20. The root cause is a signed integer overflow. The driver likely performs calculations with user-supplied input related to video buffer sizes or offsets. If the input is crafted maliciously, these calculations can result in a value that exceeds the maximum representable value for a signed integer. This overflow can then lead to incorrect memory allocation, out-of-bounds reads or writes, or other memory corruption issues. Specifically, the overflow likely occurs during calculations related to the size of the data being read or the offset within the video buffer. This could be triggered by manipulating parameters passed to the read() system call when interacting with the bttv device. The lack of proper input validation allows for the creation of a crafted input that causes the overflow, leading to a buffer overflow or other memory corruption.