UBUNTU-CVE-2026-80827

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UBUNTU-CVE-2026-80827

Summary:

Details: In the Linux kernel, the following vulnerability has been resolved: USB: serial: option: fix slab OOB read in interrupt URB callback The interrupt URB buffer is allocated in setup_port_interrupt_in() based on the endpoint's wMaxPacketSize: buffer_size = usb_endpoint_maxp(epd); port->interrupt_in_buffer = kmalloc(buffer_size, GFP_KERNEL); When a USB device declares wMaxPacketSize = 8 on its interrupt IN endpoint, the buffer is allocated from kmalloc-8 cache (exactly 8 bytes). If the device sends a short packet (actual_length < wMaxPacketSize), the URB completes with status == 0 and the callback proceeds to read: data[sizeof(struct usb_ctrlrequest)] which evaluates to data[8], accessing 1 byte beyond the allocated 8-byte buffer. This results in a slab out-of-bounds read. Fix this by adding the missing bounds check: first verify that the actual length is large enough to contain the struct usb_ctrlrequest header before accessing req_pkt->bRequestType and req_pkt->bRequest, and then verify that there is an additional byte for the modem signal state before reading data[sizeof(struct usb_ctrlrequest)] inside the conditional. Use sizeof(*req_pkt) instead of sizeof(struct usb_ctrlrequest) for consistency. [ johan: use dev_err(); split signals declaration and initialisation ]

References: https://ubuntu.com/security/CVE-2026-80827, https://www.cve.org/CVERecord?id=CVE-2026-80827, https://git.kernel.org/linus/885d802f544ca7bfa8f3984d94233cce715bb6b3