In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: Use snd_card_free_when_closed() at disconnection The USB disconnect callback is supposed to be short and not too-long waiting. OTOH, the current code uses snd_card_free() at disconnection, but this waits for the close of all used fds, hence it can take long. It eventually blocks the upper layer USB ioctls, which may trigger a soft lockup. An easy workaround is to replace snd_card_free() with snd_card_free_when_closed(). This variant returns immediately while the release of resources is done asynchronously by the card device release at the last close. This patch also splits the code to the disconnect and the free phases; the former is called immediately at the USB disconnect callback while the latter is called from the card destructor.
https://git.kernel.org/stable/c/ebad462eec93b0f701dfe4de98990e7355283801
https://git.kernel.org/stable/c/dd0de8cb708951cebf727aa045e8242ba651bb52
https://git.kernel.org/stable/c/cadf1d8e9ddcd74584ec961aeac14ac549b261d8
https://git.kernel.org/stable/c/b04dcbb7f7b1908806b7dc22671cdbe78ff2b82c
https://git.kernel.org/stable/c/a3f9314752dbb6f6aa1f0f2b4c58243bda800738
https://git.kernel.org/stable/c/4dd821dcbfcecf7af6a08370b0b217cde2818acf
https://git.kernel.org/stable/c/4507a8b9b30344c5ddd8219945f446d47e966a6d
https://git.kernel.org/stable/c/3993edf44d3df7b6e8c753eac6ac8783473fcbab
https://git.kernel.org/stable/c/237f3faf0177bdde728fa3106d730d806436aa4d