• Ard Biesheuvel's avatar
    memremap: check pfn validity before passing to pfn_to_page() · ac343e88
    Ard Biesheuvel authored
    In memremap's helper function try_ram_remap(), we dereference a struct
    page pointer that was derived from a PFN that is known to be covered by
    a 'System RAM' iomem region, and is thus assumed to be a 'valid' PFN,
    i.e., a PFN that has a struct page associated with it and is covered by
    the kernel direct mapping.
    
    However, the assumption that there is a 1:1 relation between the System
    RAM iomem region and the kernel direct mapping is not universally valid
    on all architectures, and on ARM and arm64, 'System RAM' may include
    regions for which pfn_valid() returns false.
    
    Generally speaking, both __va() and pfn_to_page() should only ever be
    called on PFNs/physical addresses for which pfn_valid() returns true, so
    add that check to try_ram_remap().
    Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    ac343e88
memremap.c 11.3 KB