CVE-2024-26660

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

drm/amd/display: Implement bounds check for stream encoder creation in DCN301

stream_enc_regs array is an array of dcn10_stream_enc_registers structures. The array is initialized with four elements, corresponding to the four calls to stream_enc_regs() in the array initializer. This means that valid indices for this array are 0, 1, 2, and 3.

The error message stream_enc_regs 4 <= 5 below, is indicating that there is an attempt to access this array with an index of 5, which is out of bounds. This could lead to undefined behavior

Here, eng_id is used as an index to access the stream_enc_regs array. If eng_id is 5, this would result in an out-of-bounds access on the stream_enc_regs array.

Thus fixing Buffer overflow error in dcn301_stream_encoder_create reported by Smatch: drivers/gpu/drm/amd/amdgpu/../display/dc/resource/dcn301/dcn301_resource.c:1011 dcn301_stream_encoder_create() error: buffer overflow stream_enc_regs 4 <= 5

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/42442f74314d41ddc68227047036fa3e78940054
• https://git.kernel.org/stable/c/58fca355ad37dcb5f785d9095db5f748b79c5dc2
• https://git.kernel.org/stable/c/a938eab9586eea31cfd129a507f552efae14d738
• https://git.kernel.org/stable/c/cd9bd10c59e3c1446680514fd3097c5b00d3712d
• https://git.kernel.org/stable/c/efdd665ce1a1634b8c1dad5e7f6baaef3e131d0a
• https://git.kernel.org/stable/c/42442f74314d41ddc68227047036fa3e78940054
• https://git.kernel.org/stable/c/58fca355ad37dcb5f785d9095db5f748b79c5dc2
• https://git.kernel.org/stable/c/a938eab9586eea31cfd129a507f552efae14d738
• https://git.kernel.org/stable/c/cd9bd10c59e3c1446680514fd3097c5b00d3712d
• https://git.kernel.org/stable/c/efdd665ce1a1634b8c1dad5e7f6baaef3e131d0a