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SubjectRe: [PATCH v4] i2c: busses: i2c-pxa.c: Fix for possible null pointer dereference
Hi,

> res = platform_get_resource(dev, IORESOURCE_MEM, 0);
> irq = platform_get_irq(dev, 0);
> - if (res == NULL || irq < 0) {
> - ret = -ENODEV;
> - goto eclk;
> - }
> + if (res == NULL || irq < 0)
> + return -ENODEV;

No need to check for valid 'res' here...

>
> - if (!request_mem_region(res->start, resource_size(res), res->name)) {
> - ret = -ENOMEM;
> - goto eclk;
> - }
> + if (!devm_request_mem_region(&dev->dev, res->start,
> + resource_size(res), res->name))
> + return -ENOMEM;

... and no need to use 'devm_request_mem_region' ...

> - i2c->reg_base = ioremap(res->start, resource_size(res));
> - if (!i2c->reg_base) {
> - ret = -EIO;
> - goto eremap;
> - }
> + i2c->reg_base = devm_ioremap_resource(&adev->dev, res));
> + if (IS_ERR(i2c->reg_base))
> + return -EIO;

... because devm_ioremap_resource does all that for you. Also, don't
return -EIO but the PTR_ERR given from the function. Just check other
drivers how they do it.

>
> i2c->reg_ibmr = i2c->reg_base + pxa_reg_layout[i2c_type].ibmr;
> i2c->reg_idbr = i2c->reg_base + pxa_reg_layout[i2c_type].idbr;
> @@ -1227,10 +1218,12 @@ static int i2c_pxa_probe(struct platform_device *dev)
> i2c->adap.algo = &i2c_pxa_pio_algorithm;
> } else {
> i2c->adap.algo = &i2c_pxa_algorithm;
> - ret = request_irq(irq, i2c_pxa_handler, IRQF_SHARED,
> - dev_name(&dev->dev), i2c);
> - if (ret)
> - goto ereqirq;
> + ret = devm_request_irq(&dev->dev, irq, i2c_pxa_handler,
> + IRQF_SHARED, dev_name(&dev->dev), i2c);
> + if (ret) {
> + clk_disable_unprepare(i2c->clk);
> + return ret;

Maybe you should make a error path with 'goto' out of it...


> + }
> }
>
> i2c_pxa_reset(i2c);
> @@ -1244,7 +1237,7 @@ static int i2c_pxa_probe(struct platform_device *dev)
> ret = i2c_add_numbered_adapter(&i2c->adap);
> if (ret < 0) {
> printk(KERN_INFO "I2C: Failed to add bus\n");
> - goto eadapt;
> + return ret;

... since you forgot disable_unprepare here and could simply reuse it.


> }
>
> platform_set_drvdata(dev, i2c);
> @@ -1257,20 +1250,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
> dev_name(&i2c->adap.dev));
> #endif
> return 0;
> -
> -eadapt:
> - if (!i2c->use_pio)
> - free_irq(irq, i2c);
> -ereqirq:
> - clk_disable_unprepare(i2c->clk);
> - iounmap(i2c->reg_base);
> -eremap:
> - clk_put(i2c->clk);
> -eclk:
> - kfree(i2c);
> -emalloc:
> - release_mem_region(res->start, resource_size(res));
> - return ret;
> }

You forgot to cleanup the remove function.

BTW I forgot, can you test this patch on real hardware? If not, is there
somebody who does?

All the best,

Wolfram

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