CVE-2026-43340comedi: Reinit dev->spinlock between attachments to low-level drivers

Official description

In the Linux kernel, the following vulnerability has been resolved: comedi: Reinit dev->spinlock between attachments to low-level drivers `struct comedi_device` is the main controlling structure for a COMEDI device created by the COMEDI subsystem. It contains a member `spinlock` containing a spin-lock that is initialized by the COMEDI subsystem, but is reserved for use by a low-level driver attached to the COMEDI device (at least since commit 25436dc9d84f ("Staging: comedi: remove RT code")). Some COMEDI devices (those created on initialization of the COMEDI subsystem when the "comedi.comedi_num_legacy_minors" parameter is non-zero) can be attached to different low-level drivers over their lifetime using the `COMEDI_DEVCONFIG` ioctl command. This can result in inconsistent lock states being reported when there is a mismatch in the spin-lock locking levels used by each low-level driver to which the COMEDI device has been attached. Fix it by reinitializing `dev->spinlock` before calling the low-level driver's `attach` function pointer if `CONFIG_LOCKDEP` is enabled.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/3181c34b415c5464be9d34bff3e43ef63b747039
• https://git.kernel.org/stable/c/2b1f49e4fdff3ef0f8e9158bbb5b149e06287560
• https://git.kernel.org/stable/c/4d5ffe524903a30e2e0da7d16841a56bec2de55c
• https://git.kernel.org/stable/c/c01bcc67a9a692d65508ebd480405b5e77d562b7
• https://git.kernel.org/stable/c/430291d8f3884f57ae0057049b0ca291453e29e1
• https://git.kernel.org/stable/c/b89c026227712c367950bbae055a5b31073d3b30
• https://git.kernel.org/stable/c/83134a7a176ce5b4b19b6edecf4360e8d98d1a5a
• https://git.kernel.org/stable/c/4b9a9a6d71e3e252032f959fb3895a33acb5865c