ALSA: timer: Set lower bound of start tick time

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Set lower bound of start tick time Currently ALSA timer doesn't have the lower limit of the start tick time, and it allows a very small size, e.g. 1 tick with 1ns resolution for hrtimer. Such a situation may lead to an unexpected RCU stall, where the callback repeatedly queuing the expire update, as reported by fuzzer. This patch introduces a sanity check of the timer start tick time, so that the system returns an error when a too small start size is set. As of this patch, the lower limit is hard-coded to 100us, which is small enough but can still work somehow.

References

• https://git.kernel.org/stable/c/68396c825c43664b20a3a1ba546844deb2b4e48f
• https://git.kernel.org/stable/c/74bfb8d90f2601718ae203faf45a196844c01fa1
• https://git.kernel.org/stable/c/bdd0aa055b8ec7e24bbc19513f3231958741d0ab
• https://git.kernel.org/stable/c/83f0ba8592b9e258fd80ac6486510ab1dcd7ad6e
• https://git.kernel.org/stable/c/ceab795a67dd28dd942d0d8bba648c6c0f7a044b
• https://git.kernel.org/stable/c/2c95241ac5fc90c929d6c0c023e84bf0d30e84c3
• https://git.kernel.org/stable/c/abb1ad69d98cf1ff25bb14fff0e7c3f66239e1cd
• https://git.kernel.org/stable/c/4a63bd179fa8d3fcc44a0d9d71d941ddd62f0c4e