CVE-2026-98769: usb: gadget: f_uac1_legacy: validate bRequest index in generic_{set,get}_cmd
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: fuac1legacy: validate bRequest index in generic{set,get}cmd
genericsetcmd() and genericgetcmd() use the low nibble of ctrl->bRequest as an index into con->data[]:
u8 cmd = (ctrl->bRequest & 0x0F); / 0 .. 15 / ... con->data[cmd] = value; / OOB when cmd >= 5 /
struct usbaudiocontrol (include/linux/usb/audio.h) declares data as a 5-element array, so indices 5 through 15 write (or read) up to 44 bytes past the end of the array on the heap.
A malicious USB host can craft a class-specific SETCUR / GETCUR request with an arbitrary bRequest value, triggering the out-of-bounds access from an IRQ completion handler with no further preconditions.
Add an ARRAYSIZE() guard to both functions.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
In the Linux kernel USB gadget UAC1 legacy driver, add an ARRAY_SIZE() bounds check to both generic_set_cmd() and generic_get_cmd() so the low-nibble bRequest index cannot access con->data[] outside its 5-element array.