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dma-direct: check for overflows on 32 bit DMA addresses

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As seen on the new Raspberry Pi 4 and sta2x11's DMA implementation it is
possible for a device configured with 32 bit DMA addresses and a partial
DMA mapping located at the end of the address space to overflow. It
happens when a higher physical address, not DMAable, is translated to
it's DMA counterpart.

For example the Raspberry Pi 4, configurable up to 4 GB of memory, has
an interconnect capable of addressing the lower 1 GB of physical memory
with a DMA offset of 0xc0000000. It transpires that, any attempt to
translate physical addresses higher than the first GB will result in an
overflow which dma_capable() can't detect as it only checks for
addresses bigger then the maximum allowed DMA address.

Fix this by verifying in dma_capable() if the DMA address range provided
is at any point lower than the minimum possible DMA address on the bus.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Nicolas Saenz Julienne 2019-11-07 16:06:44 +01:00 committed by Christoph Hellwig
parent 5e76f56457
commit b12d66278d
1 changed files with 10 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

12
include/linux/dma-direct.h
View file

@ -3,8 +3,11 @@
#define _LINUX_DMA_DIRECT_H 1 #define _LINUX_DMA_DIRECT_H 1
#include <linux/dma-mapping.h> #include <linux/dma-mapping.h>
#include <linux/memblock.h> /* for min_low_pfn */
#include <linux/mem_encrypt.h> #include <linux/mem_encrypt.h>
static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
#ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
#include <asm/dma-direct.h> #include <asm/dma-direct.h>
#else #else
@ -24,11 +27,16 @@ static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dev_addr)
static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size) static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
{ {
dma_addr_t end = addr + size - 1;
if (!dev->dma_mask) if (!dev->dma_mask)
return false; return false;
return addr + size - 1 <= if (!IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT) &&
min_not_zero(*dev->dma_mask, dev->bus_dma_mask); min(addr, end) < phys_to_dma(dev, PFN_PHYS(min_low_pfn)))
return false;
return end <= min_not_zero(*dev->dma_mask, dev->bus_dma_mask);
} }
#endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */ #endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */