CVE-2024-57953

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

rtc: tps6594: Fix integer overflow on 32bit systems

The problem is this multiply in tps6594_rtc_set_offset()

tmp = offset * TICKS_PER_HOUR;

The tmp variable is an s64 but offset is a long in the (-277774)-277774 range. On 32bit systems a long can hold numbers up to approximately two billion. The number of TICKS_PER_HOUR is really large, (32768 * 3600) or roughly a hundred million. When you start multiplying by a hundred million it doesnt take long to overflow the two billion mark.

Probably the safest way to fix this is to change the type of TICKS_PER_HOUR to long long because its such a large number.

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/09c4a610153286cef54d4f0c85398f4e32fc227e
• https://git.kernel.org/stable/c/5127f3cbfc78a7b301b86328247230bec47e0bb3
• https://git.kernel.org/stable/c/53b0c7b15accb18d15d95c7fe68f61630ebfd1ca