linux-kernel - Re: [PATCH] PCI/PTM: Fix memory leak in pcie_ptm_create

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Message-ID: <20260114163957.GA815952@bhelgaas>
Date: Wed, 14 Jan 2026 10:39:57 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: Aadityarangan Shridhar Iyengar <adiyenga@...co.com>,
	bhelgaas@...gle.com, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI/PTM: Fix memory leak in pcie_ptm_create_debugfs()
 error path

On Wed, Jan 14, 2026 at 12:58:56PM +0530, Manivannan Sadhasivam wrote:
> On Sun, Jan 11, 2026 at 10:06:50PM +0530, Aadityarangan Shridhar Iyengar wrote:
> > In pcie_ptm_create_debugfs(), if devm_kasprintf() fails after successfully
> > allocating ptm_debugfs with kzalloc(), the function returns NULL without
> > freeing the allocated memory, resulting in a memory leak.
> > 
> > Fix this by adding kfree(ptm_debugfs) before returning NULL in the
> > devm_kasprintf() error path.
> > 
> > This leak is particularly problematic during memory pressure situations
> > where devm_kasprintf() is more likely to fail, potentially compounding
> > the memory exhaustion issue.
> > 
> > Fixes: 132833405e61 ("PCI: Add debugfs support for exposing PTM context")
> > Signed-off-by: Aadityarangan Shridhar Iyengar <adiyenga@...co.com>
> > ---
> >  drivers/pci/pcie/ptm.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> > index ed0f9691e7d1..09c0167048a3 100644
> > --- a/drivers/pci/pcie/ptm.c
> > +++ b/drivers/pci/pcie/ptm.c
> > @@ -542,8 +542,10 @@ struct pci_ptm_debugfs *pcie_ptm_create_debugfs(struct device *dev, void *pdata,
> >  		return NULL;
> >  
> >  	dirname = devm_kasprintf(dev, GFP_KERNEL, "pcie_ptm_%s", dev_name(dev));
> > -	if (!dirname)
> > +	if (!dirname) {
> > +		kfree(ptm_debugfs);
> >  		return NULL;
> > +	}
> 
> Thanks for spotting the leak. I also forgot to remove it in
> pcie_ptm_destroy_debugfs(). Since this one got applied, Bjorn could you please
> squash the below fix as well?
> 
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index ed0f9691e7d1..2c27bee0773d 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -574,6 +574,7 @@ void pcie_ptm_destroy_debugfs(struct pci_ptm_debugfs *ptm_debugfs)
>  
>         mutex_destroy(&ptm_debugfs->lock);
>         debugfs_remove_recursive(ptm_debugfs->debugfs);
> +       kfree(ptm_debugfs);
>  }
>  EXPORT_SYMBOL_GPL(pcie_ptm_destroy_debugfs);
>  #endif
> 
> For this patch,
> 
> Reviewed-by: Manivannan Sadhasivam <mani@...nel.org>

Added the fix and your Reviewed-by, thanks!