Re: [PATCH v3] usb: xhci: Fix memory leak in xhci_disable_slot()

[Mathias Nyman]

On 1/29/26 10:56, Michal Pecio wrote:
> On Fri,  9 Jan 2026 04:54:10 +0000, Zilin Guan wrote:
> > xhci_alloc_command() allocates a command structure and, when the
> > second argument is true, also allocates a completion structure.
> > Currently, the error handling path in xhci_disable_slot() only frees
> > the command structure using kfree(), causing the completion structure
> > to leak.
> >
> > Use xhci_free_command() instead of kfree(). xhci_free_command()
> > correctly frees both the command structure and the associated
> > completion structure. Since the command structure is allocated with
> > zero-initialization, command->in_ctx is NULL and will not be
> > erroneously freed by xhci_free_command().
> >
> > This bug was found using an experimental static analysis tool we are
> > developing. The tool is based on the LLVM framework and is
> > specifically designed to detect memory management issues. It is
> > currently under active development and not yet publicly available,
> > but we plan to open-source it after our research is published.
> >
> > The bug was originally detected on v6.13-rc1 using our static analysis
> > tool, and we have verified that the issue persists in the latest
> > mainline kernel.
> >
> > We performed build testing on x86_64 with allyesconfig using
> > GCC=11.4.0. Since triggering these error paths in xhci_disable_slot()
> > requires specific hardware conditions or abnormal state, we were
> > unable to construct a test case to reliably trigger these specific
> > error paths at runtime.
> >
> > Fixes: 7faac1953ed1 ("xhci: avoid race between disable slot command
> > and host runtime suspend") CC: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Zilin Guan <zilin@xxxxxxxxxx>
>
> This looks like correct fix to an actual bug, but it seems that it has
> been missed? I see it neither in usb-next nor usb-linus or mainline.
>
> The leak is still there, even if arguably a small and rare one.

Thanks for the reminder.
We are so late in the cycle now that I'll send it after rc1

Thanks
Mathias