drivers: dma-mapping: Do not leave an invalid area->pages pointer in dma_common_conti...

drivers: dma-mapping: Do not leave an invalid area->pages pointer in dma_common_contiguous_remap()

The dma_common_pages_remap() function allocates a vm_struct object and
initialises the pages pointer to value passed as argument. However, when
this function is called dma_common_contiguous_remap(), the pages array
is only temporarily allocated, being freed shortly after
dma_common_contiguous_remap() returns. Architecture code checking the
validity of an area->pages pointer would incorrectly dereference already
freed pointers. This has been exposed by the arm64 commit 44176bb38fa4
("arm64: Add support for DMA_ATTR_FORCE_CONTIGUOUS to IOMMU").

Fixes: 513510ddba96 ("common: dma-mapping: introduce common remapping functions")
Cc: Greg Kroah-Hartman <[email protected]>
Reported-by: Andrzej Hajda <[email protected]>
Acked-by: Laura Abbott <[email protected]>
Reviewed-by: Robin Murphy <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>