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

[Michal Pecio]

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.

Regards,
Michal