CVE-2026-53194

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> USB: serial: kl5kusb105: fix bulk-out buffer overflow<br /> <br /> klsi_105_prepare_write_buffer() is called by the generic write path<br /> with the bulk-out buffer and its size (bulk_out_size, 64 bytes). It<br /> stores a two-byte length header at the start of the buffer and copies<br /> the payload from the write fifo starting at buf + KLSI_HDR_LEN, but<br /> passes the full buffer size as the number of bytes to copy:<br /> <br /> count = kfifo_out_locked(&amp;port-&gt;write_fifo, buf + KLSI_HDR_LEN,<br /> size, &amp;port-&gt;lock);<br /> <br /> When the fifo holds at least size bytes, size bytes are copied starting<br /> two bytes into the size-byte buffer, writing KLSI_HDR_LEN bytes past its<br /> end. Copy at most size - KLSI_HDR_LEN bytes instead, leaving room for<br /> the header as safe_serial already does.<br /> <br /> Writing bulk_out_size or more bytes to the tty triggers a slab<br /> out-of-bounds write, observed with KASAN by emulating the device with<br /> dummy_hcd and raw-gadget:<br /> <br /> BUG: KASAN: slab-out-of-bounds in kfifo_copy_out+0x83/0xc0<br /> Write of size 64 at addr ffff888112c62202 by task python3<br /> kfifo_copy_out<br /> klsi_105_prepare_write_buffer [kl5kusb105]<br /> usb_serial_generic_write_start [usbserial]<br /> Allocated by task 139:<br /> usb_serial_probe [usbserial]<br /> The buggy address is located 2 bytes inside of allocated 64-byte region<br /> <br /> The out-of-bounds write no longer occurs with this change applied.