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dma-direct: Fix potential NULL pointer dereference

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When booting the kernel v5.9-rc4 on a VM, the kernel would panic when
printing a warning message in swiotlb_map(). The dev->dma_mask must not
be a NULL pointer when calling the dma mapping layer. A NULL pointer
check can potentially avoid the panic.

Signed-off-by: Thomas Tai <thomas.tai@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Thomas Tai 2020-09-17 18:43:03 +02:00 • committed by Christoph Hellwig
parent a92df4f62f
commit f959dcd6dd
2 changed files with 11 additions and 3 deletions
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3
include/linux/dma-direct.h
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@ -62,9 +62,6 @@ 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)
return false;
if (is_ram && !IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT) &&
min(addr, end) < phys_to_dma(dev, PFN_PHYS(min_low_pfn)))
return false;