dmaengine: usb-dmac: Avoid format-overflow warning

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@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240110222210.193479-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
index a9b4302..f7cd0ca 100644 (file)
--- 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]);