CVE-2026-43380

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

hwmon: (pmbus/q54sj108a2) fix stack overflow in debugfs read

The q54sj108a2_debugfs_read function suffers from a stack buffer overflow due to incorrect arguments passed to bin2hex(). The function currently passes data as the destination and data_char as the source.

Because bin2hex() converts each input byte into two hex characters, a 32-byte block read results in 64 bytes of output. Since data is only 34 bytes (I2C_SMBUS_BLOCK_MAX + 2), this writes 30 bytes past the end of the buffer onto the stack.

Additionally, the arguments were swapped: it was reading from the zero-initialized data_char and writing to data, resulting in all-zero output regardless of the actual I2C read.

Fix this by:

1. Expanding data_char to 66 bytes to safely hold the hex output.
2. Correcting the bin2hex() argument order and using the actual read count.
3. Using a pointer to select the correct output buffer for the final simple_read_from_buffer call.

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/24a7b9daa103fa963b3fd37d8805b23e01621976
• https://git.kernel.org/stable/c/25dd70a03b1f5f3aa71e1a5091ecd9cd2a13ee43
• https://git.kernel.org/stable/c/52db5ef163c96f916d424e472fb17aadc35a9f7a
• https://git.kernel.org/stable/c/73a7a345816946d276ad2c46c8bb771de67cfc46
• https://git.kernel.org/stable/c/a0fc1b9c738fba231f190ab960c83202722efee5
• https://git.kernel.org/stable/c/b48a0f8d4541a4f6651dc9a64430ce9fdf5c120b
• https://git.kernel.org/stable/c/c59090c50f62a17129fc4c5407bc4071305a9e82