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

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Message-ID: <40db668d-8e8b-4782-8a0b-4a0e9965f086@wanadoo.fr>
Date: Wed, 21 Aug 2024 12:00:20 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Philipp Stanner <pstanner@...hat.com>
Cc: alexandre.torgue@...s.st.com, alvaro.karsz@...id-run.com,
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Subject: Re: [PATCH v2 7/9] vdpa: solidrun: Fix potential UB bug with devres

Le 21/08/2024 à 09:18, Philipp Stanner a écrit :
> 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>
> ---
>   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)

snet_open_vf_bar() also needs the same modification (see Andy's comment 
on patch 8/9)

CJ

>   {
> -	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");