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Date:   Thu, 28 May 2020 06:29:08 -0700
From:   Andi Kleen <ak@linux.intel.com>
To:     kan.liang@linux.intel.com
Cc:     peterz@infradead.org, mingo@redhat.com,
        linux-kernel@vger.kernel.org, David.Laight@aculab.com
Subject: Re: [PATCH V2 2/3] perf/x86/intel/uncore: Record the size of mapped
 area
Message-ID: <20200528132908.GG611145@tassilo.jf.intel.com>
References: <1590671727-99311-1-git-send-email-kan.liang@linux.intel.com>
 <1590671727-99311-2-git-send-email-kan.liang@linux.intel.com>
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On Thu, May 28, 2020 at 06:15:26AM -0700, kan.liang@linux.intel.com wrote:
> -	box->io_addr = ioremap(addr, SNB_UNCORE_PCI_IMC_MAP_SIZE);
> +	if (!type->mmio_map_size) {
> +		pr_warn("perf uncore: Cannot ioremap for %s. Size of map area is 0.\n",
> +			type->name);
> +		return;
> +	}

Is that likely that the size is 0?

In any case you have to test the return value of ioremap. So I would rather
test the address for 0 than the size.

Similar in other code below.

I thought you were going to add a range check based on the size to the
actual access. Did I miss it in the patch?

-Andi