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[79.181.91.42]) by smtp.gmail.com with ESMTPSA id l129sm38783525vki.45.2019.07.22.11.57.07 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 22 Jul 2019 11:57:09 -0700 (PDT) Date: Mon, 22 Jul 2019 14:57:04 -0400 From: "Michael S. Tsirkin" To: Auger Eric Subject: Re: [PATCH v2] dma-mapping: Use dma_get_mask in dma_addressing_limited Message-ID: <20190722145639-mutt-send-email-mst@kernel.org> References: <20190722165149.3763-1-eric.auger@redhat.com> <77ba1061-08b6-421e-a6dd-d5db9851325b@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <77ba1061-08b6-421e-a6dd-d5db9851325b@redhat.com> Cc: jasowang@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, eric.auger.pro@gmail.com, robin.murphy@arm.com, hch@lst.de X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Mon, Jul 22, 2019 at 06:56:49PM +0200, Auger Eric wrote: > Hi Christoph, > > On 7/22/19 6:51 PM, Eric Auger wrote: > > We currently have cases where the dma_addressing_limited() gets > > called with dma_mask unset. This causes a NULL pointer dereference. > > > > Use dma_get_mask() accessor to prevent the crash. > > > > Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper") > > Signed-off-by: Eric Auger > > As a follow-up of my last email, here is a patch featuring > dma_get_mask(). But you don't have the WARN_ON_ONCE anymore, pointing > out suspect users. OTOH these users then simply become okay so no need for WARN_ON_ONCE then :) > Feel free to pick up your preferred approach > > Thanks > > Eric > > > > --- > > > > v1 -> v2: > > - was [PATCH 1/2] dma-mapping: Protect dma_addressing_limited > > against NULL dma_mask > > - Use dma_get_mask > > --- > > include/linux/dma-mapping.h | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > > index e11b115dd0e4..f7d1eea32c78 100644 > > --- a/include/linux/dma-mapping.h > > +++ b/include/linux/dma-mapping.h > > @@ -689,8 +689,8 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask) > > */ > > static inline bool dma_addressing_limited(struct device *dev) > > { > > - return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) < > > - dma_get_required_mask(dev); > > + return min_not_zero(dma_get_mask(dev), dev->bus_dma_mask) < > > + dma_get_required_mask(dev); > > } > > > > #ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS > > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu