lkml.org 
[lkml]   [2017]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Date
    Subject[PATCH 3.16 063/233] drivers: char: mem: Check for address space wraparound with mmap()
    3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Julius Werner <jwerner@chromium.org>

    commit b299cde245b0b76c977f4291162cf668e087b408 upstream.

    /dev/mem currently allows mmap() mappings that wrap around the end of
    the physical address space, which should probably be illegal. It
    circumvents the existing STRICT_DEVMEM permission check because the loop
    immediately terminates (as the start address is already higher than the
    end address). On the x86_64 architecture it will then cause a panic
    (from the BUG(start >= end) in arch/x86/mm/pat.c:reserve_memtype()).

    This patch adds an explicit check to make sure offset + size will not
    wrap around in the physical address type.

    Signed-off-by: Julius Werner <jwerner@chromium.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/char/mem.c | 5 +++++
    1 file changed, 5 insertions(+)

    --- a/drivers/char/mem.c
    +++ b/drivers/char/mem.c
    @@ -329,6 +329,11 @@ static const struct vm_operations_struct
    static int mmap_mem(struct file *file, struct vm_area_struct *vma)
    {
    size_t size = vma->vm_end - vma->vm_start;
    + phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
    +
    + /* It's illegal to wrap around the end of the physical address space. */
    + if (offset + (phys_addr_t)size < offset)
    + return -EINVAL;

    if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
    return -EINVAL;
    \
     
     \ /
      Last update: 2017-09-10 01:34    [W:2.121 / U:0.100 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site