IT

Tracker / CVE-2025-38480

CVE-2025-38480

Medium 5.5

In the Linux kernel, the following vulnerability has been resolved: comedi: Fix use of uninitialized data in insn_rw_emulate_bits() For Comedi `INSN_READ` and `INSN_WRITE` instructions on "digital" subdevices (subdevice types `COMEDI_SUBD_DI`, `COMEDI_SUBD_DO`, and `COMEDI_SUBD_DIO`), it is common for the subdevice driver not to have `insn_read` and `insn_write` handler functions, but to have an `insn_bits` handler function for handling Comedi `INSN_BITS` instructions. In that case, the subdevice's `insn_read` and/or `insn_write` function handler pointers are set to point to the `insn_rw_emulate_bits()` function by `__comedi_device_postconfig()`. For `INSN_WRITE`, `insn_rw_emulate_bits()` currently assumes that the supplied `data[0]` value is a valid copy from user memory. It will at least exist because `do_insnlist_ioctl()` and `do_insn_ioctl()` in "comedi_fops.c" ensure at lease `MIN_SAMPLES` (16) elements are allocated. However, if `insn->n` is 0 (which is allowable for `INSN_READ` and `INSN_WRITE` instructions, then `data[0]` may contain uninitialized data, and certainly contains invalid data, possibly from a different instruction in the array of instructions handled by `do_insnlist_ioctl()`. This will result in an incorrect value being written to the digital output channel (or to the digital input/output channel if configured as an output), and may be reflected in the internal saved state of the channel. Fix it by returning 0 early if `insn->n` is 0, before reaching the code that accesses `data[0]`. Previously, the function always returned 1 on success, but it is supposed to be the number of data samples actually read or written up to `insn->n`, which is 0 in this case.

Affected products and versions

debian debian_linux
linux linux_kernel
linux linux_kernel · 2.6.29 → 5.4.297
linux linux_kernel · 5.11 → 5.15.190
linux linux_kernel · 5.16 → 6.1.147
linux linux_kernel · 5.5 → 5.10.241
linux linux_kernel · 6.13 → 6.15.8
linux linux_kernel · 6.2 → 6.6.100
linux linux_kernel · 6.7 → 6.12.40

Analysis

This page is not indexable yet.Until it carries original analysis — what it actually exposes, how to check in two minutes whether a system was touched, what to do if it was — the page stays noindex. The database decides that, not the template.

References