netdev - Re: [PATCH v2 7/9] vdpa: solidrun: Fix potential UB bug with devres

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Message-ID: <20240821081213-mutt-send-email-mst@kernel.org>
Date: Wed, 21 Aug 2024 08:12:50 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Philipp Stanner <pstanner@...hat.com>
Cc: Jonathan Corbet <corbet@....net>, Jens Axboe <axboe@...nel.dk>,
	Wu Hao <hao.wu@...el.com>, Tom Rix <trix@...hat.com>,
	Moritz Fischer <mdf@...nel.org>, Xu Yilun <yilun.xu@...el.com>,
	Andy Shevchenko <andy@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Alvaro Karsz <alvaro.karsz@...id-run.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Richard Cochran <richardcochran@...il.com>,
	Mark Brown <broonie@...nel.org>,
	David Lechner <dlechner@...libre.com>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	Damien Le Moal <dlemoal@...nel.org>, Hannes Reinecke <hare@...e.de>,
	Keith Busch <kbusch@...nel.org>, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
	linux-fpga@...r.kernel.org, linux-gpio@...r.kernel.org,
	netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org,
	virtualization@...ts.linux.dev, stable@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: Re: [PATCH v2 7/9] vdpa: solidrun: Fix potential UB bug with devres

On Wed, Aug 21, 2024 at 09:18:40AM +0200, Philipp Stanner wrote:
> In psnet_open_pf_bar() a string later passed to pcim_iomap_regions() is
> placed on the stack. Neither pcim_iomap_regions() nor the functions it
> calls copy that string.
> 
> Should the string later ever be used, this, consequently, causes
> undefined behavior since the stack frame will by then have disappeared.
> 
> Fix the bug by allocating the string on the heap through
> devm_kasprintf().
> 
> Cc: stable@...r.kernel.org	# v6.3
> Fixes: 51a8f9d7f587 ("virtio: vdpa: new SolidNET DPU driver.")
> Reported-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> Closes: https://lore.kernel.org/all/74e9109a-ac59-49e2-9b1d-d825c9c9f891@wanadoo.fr/
> Suggested-by: Andy Shevchenko <andy@...nel.org>
> Signed-off-by: Philipp Stanner <pstanner@...hat.com>

I don't get why is this a part of a cleanup series -
looks like an unrelated bugfix?


> ---
>  drivers/vdpa/solidrun/snet_main.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vdpa/solidrun/snet_main.c b/drivers/vdpa/solidrun/snet_main.c
> index 99428a04068d..4d42a05d70fc 100644
> --- a/drivers/vdpa/solidrun/snet_main.c
> +++ b/drivers/vdpa/solidrun/snet_main.c
> @@ -555,7 +555,7 @@ static const struct vdpa_config_ops snet_config_ops = {
>  
>  static int psnet_open_pf_bar(struct pci_dev *pdev, struct psnet *psnet)
>  {
> -	char name[50];
> +	char *name;
>  	int ret, i, mask = 0;
>  	/* We don't know which BAR will be used to communicate..
>  	 * We will map every bar with len > 0.
> @@ -573,7 +573,10 @@ static int psnet_open_pf_bar(struct pci_dev *pdev, struct psnet *psnet)
>  		return -ENODEV;
>  	}
>  
> -	snprintf(name, sizeof(name), "psnet[%s]-bars", pci_name(pdev));
> +	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "psnet[%s]-bars", pci_name(pdev));
> +	if (!name)
> +		return -ENOMEM;
> +
>  	ret = pcim_iomap_regions(pdev, mask, name);
>  	if (ret) {
>  		SNET_ERR(pdev, "Failed to request and map PCI BARs\n");
> -- 
> 2.46.0