From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 22 Apr 2014 09:53:07 +0100 Subject: [PATCH] arm: dma-mapping: Fix mapping size value In-Reply-To: <1398062847-5770-2-git-send-email-ritesh.harjani@gmail.com> References: <1398062847-5770-1-git-send-email-ritesh.harjani@gmail.com> <1398062847-5770-2-git-send-email-ritesh.harjani@gmail.com> Message-ID: <20140422085307.GB5747@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Apr 21, 2014 at 07:47:27AM +0100, Ritesh Harjani wrote: > 68efd7d2fb("arm: dma-mapping: remove order parameter from > arm_iommu_create_mapping()") is causing kernel panic > because it wrongly sets the value of mapping->size: > > Unable to handle kernel NULL pointer dereference at virtual > address 000000a0 > pgd = e7a84000 > [000000a0] *pgd=00000000 > ... > PC is at bitmap_clear+0x48/0xd0 > LR is at __iommu_remove_mapping+0x130/0x164 > > Fix it by correcting mapping->size value. > > Signed-off-by: Ritesh Harjani > Acked-by: Laurent Pinchart > --- > arch/arm/mm/dma-mapping.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index f62aa06..6b00be1 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -1963,8 +1963,8 @@ arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size) > mapping->nr_bitmaps = 1; > mapping->extensions = extensions; > mapping->base = base; > - mapping->size = bitmap_size << PAGE_SHIFT; > mapping->bits = BITS_PER_BYTE * bitmap_size; > + mapping->size = mapping->bits << PAGE_SHIFT; Ok, but given that mapping->size is derived from mapping->bits, do we really need both of these fields in struct dma_iommu_mapping? Will