CVE-2024-35997

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

HID: i2c-hid: remove I2C_HID_READ_PENDING flag to prevent lock-up

The flag I2C_HID_READ_PENDING is used to serialize I2C operations. However, this is not necessary, because I2C core already has its own locking for that.

More importantly, this flag can cause a lock-up: if the flag is set in i2c_hid_xfer() and an interrupt happens, the interrupt handler (i2c_hid_irq) will check this flag and return immediately without doing anything, then the interrupt handler will be invoked again in an infinite loop.

Since interrupt handler is an RT task, it takes over the CPU and the flag-clearing task never gets scheduled, thus we have a lock-up.

Delete this unnecessary flag.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/0561b65fbd53d3e788c5b0222d9112ca016fd6a1
• https://git.kernel.org/stable/c/21bfca822cfc1e71796124e93b46e0d9fa584401
• https://git.kernel.org/stable/c/29e94f295bad5be59cf4271a93e22cdcf5536722
• https://git.kernel.org/stable/c/418c5575d56410c6e186ab727bf32ae32447d497
• https://git.kernel.org/stable/c/5095b93021b899f54c9355bebf36d78854c33a22
• https://git.kernel.org/stable/c/9c0f59e47a90c54d0153f8ddc0f80d7a36207d0e
• https://git.kernel.org/stable/c/b65fb50e04a95eec34a9d1bc138454a98a5578d8
• https://git.kernel.org/stable/c/c448a9fd50f77e8fb9156ff64848aa4295eb3003