Re: [BUG] KASAN: slab-use-after-free Read in comedi_poll

[Greg KH]

On Thu, Aug 20, 2026 at 02:46:00AM +0900, Jaeyoung Chung wrote:
> Hello,
> 
> We found a "KASAN: slab-use-after-free Read in comedi_poll" on Linux v7.2.
> The issue was found by our own race fuzzer. We have not analyzed the root cause,
> so we do not have a proposed fix to offer.
> 
> To reproduce the race reliably, we applied the delay patch below to the
> kernel and ran the C reproducer as root inside an x86_64 QEMU guest. The
> crash log we observed, the delay patch and the reproducer are all included
> below.
> 
> The reproducer opens /dev/comedi3, which exists if the kernel is booted
> with comedi.comedi_num_legacy_minors=4.
> 
> The following kernel config options are required to reproduce the issue:
>     CONFIG_ISA_BUS=y
>     CONFIG_COMEDI=y
>     CONFIG_COMEDI_MISC_DRIVERS=y
>     CONFIG_COMEDI_ISA_DRIVERS=y
>     CONFIG_COMEDI_PCL818=y
> 
> We hope this report is useful. Please let us know if any further
> information would help.

Please just provide a normal patch that can be applied.

thanks,

greg k-h