CVE-2023-53646

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

drm/i915/perf: add sentinel to xehp_oa_b_counters

Arrays passed to reg_in_range_table should end with empty record.

The patch solves KASAN detected bug with signature: BUG: KASAN: global-out-of-bounds in xehp_is_valid_b_counter_addr+0x2c7/0x350 [i915] Read of size 4 at addr ffffffffa1555d90 by task perf/1518

CPU: 4 PID: 1518 Comm: perf Tainted: G U 6.4.0-kasan_438-g3303d06107f3+ #1 Hardware name: Intel Corporation Meteor Lake Client Platform/MTL-P DDR5 SODIMM SBS RVP, BIOS MTLPFWI1.R00.3223.D80.2305311348 05/31/2023 Call Trace: … xehp_is_valid_b_counter_addr+0x2c7/0x350 [i915]

(cherry picked from commit 2f42c5afb34b5696cf5fe79e744f99be9b218798)

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/21d92025e80629fd5c25cd6751f8cf38c784dd4a
• https://git.kernel.org/stable/c/785b3f667b4bf98804cad135005e964df0c750de