CVE-2022-49051

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

net: usb: aqc111: Fix out-of-bounds accesses in RX fixup

aqc111_rx_fixup() contains several out-of-bounds accesses that can be triggered by a malicious (or defective) USB device, in particular:

• The metadata array (desc_offset..desc_offset+2*pkt_count) can be out of bounds, causing OOB reads and (on big-endian systems) OOB endianness flips.
• A packet can overlap the metadata array, causing a later OOB endianness flip to corrupt data used by a cloned SKB that has already been handed off into the network stack.
• A packet SKB can be constructed whose tail is far beyond its end, causing out-of-bounds heap data to be considered part of the SKBs data.

Found doing variant analysis. Tested it with another driver (ax88179_178a), since I dont have a aqc111 device to test it, but the code looks very similar.

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/36311fe98f55dea9200c69e2dd6d6ddb8fc94080
• https://git.kernel.org/stable/c/404998a137bcb8a926f7c949030afbe285472593
• https://git.kernel.org/stable/c/afb8e246527536848b9b4025b40e613edf776a9d
• https://git.kernel.org/stable/c/b416898442f2b6aa9f1b2f2968ce07e3abaa05f7
• https://git.kernel.org/stable/c/d90df6da50c56ad8b1a132e3cf86b6cdf8f507b7