linux-kernel - Re: [PATCH v5 1/3] PCI: Fix off by one in dma_alias

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Message-ID: <20191202170304.GA4174@infradead.org>
Date:   Mon, 2 Dec 2019 09:03:04 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     James Sewart <jamessewart@...sta.com>
Cc:     linux-pci@...r.kernel.org, Logan Gunthorpe <logang@...tatee.com>,
        Christoph Hellwig <hch@...radead.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Dmitry Safonov <dima@...sta.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Bjorn Helgaas <helgaas@...nel.org>
Subject: Re: [PATCH v5 1/3] PCI: Fix off by one in dma_alias_mask allocation
 size

On Fri, Nov 29, 2019 at 05:56:19PM +0000, James Sewart wrote:
> The number of possible devfns is 256 so the size of the bitmap for
> allocations should be U8_MAX+1.
> 
> Signed-off-by: James Sewart <jamessewart@...sta.com>
> ---
>  drivers/pci/pci.c    | 2 +-
>  drivers/pci/search.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index a97e2571a527..0a4449a30ace 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5876,7 +5876,7 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
>  void pci_add_dma_alias(struct pci_dev *dev, u8 devfn)
>  {
>  	if (!dev->dma_alias_mask)
> -		dev->dma_alias_mask = bitmap_zalloc(U8_MAX, GFP_KERNEL);
> +		dev->dma_alias_mask = bitmap_zalloc(U8_MAX+1, GFP_KERNEL);

Missing whitespaces around the "+".

> -		for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX) {
> +		for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX+1) {

Same here.