CVE-2026-80816

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CVE-2026-80816

Summary: ALSA: FCP: Use a private URB for the notification endpoint

Details: In the Linux kernel, the following vulnerability has been resolved: ALSA: FCP: Use a private URB for the notification endpoint fcp_init_notify() used mixer->urb, which snd_usb_mixer_status_create() allocates for the optional UAC2 status interrupt endpoint and mixer.c kills, resubmits and frees. On a device with that endpoint, fcp_init_notify()'s "already set up" early return fires on the status URB and returns success without doing anything. No FCP notification URB is submitted, and cmd_done is left zeroed because it is initialised past that early return and nowhere else. fcp_init() then issues init1_opcode and wait_for_completion_timeout() would crash adding to the zeroed wait.head. fcp_cleanup_urb() would also kill and free mixer.c's status URB. Use a separate URB in fcp_data, and initialise cmd_done in fcp_init_private() where fcp_data is allocated. fcp_init_notify() is reached again after suspend via fcp_reinit(), and the URB kill path in fcp_notify() completes cmd_done, leaving a stale count that would satisfy the next command's wait before the device ACKs. Use reinit_completion() to clear it.

References: https://git.kernel.org/stable/c/5da21a434171e8ecf1d992c6f1d84c0c706fd395, https://git.kernel.org/stable/c/65aceb45ca91ddb7f7ed178821f481b34da35543, https://git.kernel.org/stable/c/6db3c1d7e2872c9904e05ca8e0515920776a3c9c, https://git.kernel.org/stable/c/918b8d231c571c50a00efe92ffc8404a537a0490, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80816.json, https://nvd.nist.gov/vuln/detail/CVE-2026-80816, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git