CVE-2026-68257

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

drm/amdkfd: fix 32-bit overflow in CWSR total size calculation

total_cwsr_size was computed in 32-bit before being used as a BO/SVM allocation size. With large ctx_save_restore_area_size and debug_memory_size multiplied by the XCC count, the product can wrap, yielding an undersized CWSR save area that firmware later overruns.

Promote total_cwsr_size to u64 and use check_add_overflow()/ check_mul_overflow() in both kfd_queue_acquire_buffers() and kfd_queue_release_buffers().

(cherry picked from commit 319f7e13423ae3f486b9aea82f9ad2d6af0ee608)

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/2b0386d4293920e690c0e017708f999b93cc729b
• https://git.kernel.org/stable/c/865532d54eb57b660b1cb1b0e1755776ce21b849
• https://git.kernel.org/stable/c/abce3276c57e36c955627307469b9f009057a467
• https://git.kernel.org/stable/c/b88ffe6593607364a8c06a48c6f29e55437cdf8e