On Wed, Jan 10, 2024 at 10:22:10PM +0000, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> gcc points out that the fix-byte buffer might be too small:
> drivers/dma/sh/usb-dmac.c: In function 'usb_dmac_probe':
> drivers/dma/sh/usb-dmac.c:720:34: warning: '%u' directive writing between 1 and 10 bytes into a region of size 3 [-Wformat-overflow=]
> 720 | sprintf(pdev_irqname, "ch%u", index);
> | ^~
> In function 'usb_dmac_chan_probe',
> inlined from 'usb_dmac_probe' at drivers/dma/sh/usb-dmac.c:814:9:
> drivers/dma/sh/usb-dmac.c:720:31: note: directive argument in the range [0, 4294967294]
> 720 | sprintf(pdev_irqname, "ch%u", index);
> | ^~~~~~
> drivers/dma/sh/usb-dmac.c:720:9: note: 'sprintf' output between 4 and 13 bytes into a destination of size 5
> 720 | sprintf(pdev_irqname, "ch%u", index);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Maximum number of channels for USB-DMAC as per the driver is 1-99 so use
> u8 instead of unsigned int/int for DMAC channel indexing and make the
> pdev_irqname string long enough to avoid the warning.
>
> While at it use scnprintf() instead of sprintf() to make the code more
> robust.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
This looks like good fixes; thanks! I see n_channels is sanity checked
during the probe in usb_dmac_chan_probe(), so this looks good.
(Is there a reason not to also change n_channels to a u8?)
-Kees
> ---
> drivers/dma/sh/usb-dmac.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
> index a9b4302f6050..f7cd0cad056c 100644
> --- a/drivers/dma/sh/usb-dmac.c
> +++ b/drivers/dma/sh/usb-dmac.c
> @@ -706,10 +706,10 @@ static const struct dev_pm_ops usb_dmac_pm = {
>
> static int usb_dmac_chan_probe(struct usb_dmac *dmac,
> struct usb_dmac_chan *uchan,
> - unsigned int index)
> + u8 index)
> {
> struct platform_device *pdev = to_platform_device(dmac->dev);
> - char pdev_irqname[5];
> + char pdev_irqname[6];
> char *irqname;
> int ret;
>
> @@ -717,7 +717,7 @@ static int usb_dmac_chan_probe(struct usb_dmac *dmac,
> uchan->iomem = dmac->iomem + USB_DMAC_CHAN_OFFSET(index);
>
> /* Request the channel interrupt. */
> - sprintf(pdev_irqname, "ch%u", index);
> + scnprintf(pdev_irqname, sizeof(pdev_irqname), "ch%u", index);
> uchan->irq = platform_get_irq_byname(pdev, pdev_irqname);
> if (uchan->irq < 0)
> return -ENODEV;
> @@ -768,8 +768,8 @@ static int usb_dmac_probe(struct platform_device *pdev)
> const enum dma_slave_buswidth widths = USB_DMAC_SLAVE_BUSWIDTH;
> struct dma_device *engine;
> struct usb_dmac *dmac;
> - unsigned int i;
> int ret;
> + u8 i;
>
> dmac = devm_kzalloc(&pdev->dev, sizeof(*dmac), GFP_KERNEL);
> if (!dmac)
> @@ -869,7 +869,7 @@ static void usb_dmac_chan_remove(struct usb_dmac *dmac,
> static void usb_dmac_remove(struct platform_device *pdev)
> {
> struct usb_dmac *dmac = platform_get_drvdata(pdev);
> - int i;
> + u8 i;
> for (i = 0; i < dmac->n_channels; ++i)
> usb_dmac_chan_remove(dmac, &dmac->channels[i]);
> --
> 2.34.1
>
--
Kees Cook
