dmaengine: idxd: Fix double free in idxd_setup_wqs()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: Fix double free in idxd_setup_wqs() The clean up in idxd_setup_wqs() has had a couple bugs because the error handling is a bit subtle. It's simpler to just re-write it in a cleaner way. The issues here are: 1) If "idxd->max_wqs" is <= 0 then we call put_device(conf_dev) when "conf_dev" hasn't been initialized. 2) If kzalloc_node() fails then again "conf_dev" is invalid. It's either uninitialized or it points to the "conf_dev" from the previous iteration so it leads to a double free. It's better to free partial loop iterations within the loop and then the unwinding at the end can handle whole loop iterations. I also renamed the labels to describe what the goto does and not where the goto was located.

References

• https://git.kernel.org/stable/c/25e6146c2812487a88f619d5ff6efbdcd5b2bc31
• https://git.kernel.org/stable/c/df82c7901513fd0fc738052a8e6a330d92cc8ec9
• https://git.kernel.org/stable/c/ec5430d090d0b6ace8fefa290fc37e88930017d2
• https://git.kernel.org/stable/c/9f0e225635475b2285b966271d5e82cba74295b1
• https://git.kernel.org/stable/c/39aaa337449e71a41d4813be0226a722827ba606