CVE-2022-49642

In the Linux kernel, the following vulnerability has been resolved:

net: stmmac: dwc-qos: Disable split header for Tegra194

There is a long-standing issue with the Synopsys DWC Ethernet driver for Tegra194 where random system crashes have been observed [0]. The problem occurs when the split header feature is enabled in the stmmac driver. In the bad case, a larger than expected buffer length is received and causes the calculation of the total buffer length to overflow. This results in a very large buffer length that causes the kernel to crash. Why this larger buffer length is received is not clear, however, the feedback from the NVIDIA design team is that the split header feature is not supported for Tegra194. Therefore, disable split header support for Tegra194 to prevent these random crashes from occurring.

[0] https://lore.kernel.org/linux-tegra/b0b17697-f23e-8fa5-3757-604a86f3a095@nvidia.com/

Weakness

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• If possible, choose a language or compiler that performs automatic bounds checking.
• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
• Use libraries or frameworks that make it easier to handle numbers without unexpected consequences.
• Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
• Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
• Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values.
• Understand the programming language’s underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, “not-a-number” calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7]
• Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/92.html

References

• https://git.kernel.org/stable/c/029c1c2059e9c4b38f97a06204cdecd10cfbeb8a
• https://git.kernel.org/stable/c/2968830c9b47ce093237483c6207c61065712386
• https://git.kernel.org/stable/c/9cc8edc571b871d974b3289868553f9ce544aba6
• https://git.kernel.org/stable/c/cfa4caf3e881ad6dd366c903c34f1c7f21b857ab
• https://git.kernel.org/stable/c/d5c315a787652c35045044877a249f7d5c8a4104