جزئیات آسیب‌پذیری

In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Fix UAF at snd_timer_user_params() At releasing a timer object, e.g. when a userspace timer (CONFIG_SND_UTIMER) gets closed and snd_timer_free() is called, it tries to detach the timer instances and release the resources. However, it's still possible that other in-flight tasks are holding the timer instance where the to-be-deleted timer object is associated, and this may lead to racy accesses. Fortunately, most of ioctls dealing with the timer instance list already have the protection with register_mutex, and this also avoids such races. But, SNDRV_TIMER_IOCTL_PARAMS isn't protected, hence the concurrent ioctl may lead to use-after-free. This patch just adds the guard with register_mutex to protect snd_timer_user_params() for covering the code path as a quick workaround. It's no hot-path but rather a rarely issued ioctl, so the performance penalty doesn't matter.

• https://git.kernel.org/stable/c/38034d04d4a75bbca01df2b313ced0bcd0fa3242
• https://git.kernel.org/stable/c/3d39da65b5c422c5e5afb7d5651b0698d060a827
• https://git.kernel.org/stable/c/306427adf9b97e29e5958cb9cf3096c6151fc9ff
• https://git.kernel.org/stable/c/053a401b592be424fea9d57c789f66cd5d8cec11
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html