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drivers: char: mem: Fix wraparound check to allow mappings up to the end 

A recent fix to /dev/mem prevents mappings from wrapping around the end
of physical address space. However, the check was written in a way that
also prevents a mapping reaching just up to the end of physical address
space, which may be a valid use case (especially on 32-bit systems).
This patch fixes it by checking the last mapped address (instead of the
first address behind that) for overflow.

Fixes: b299cde245 ("drivers: char: mem: Check for address space wraparound with mmap()")
Cc: <stable@vger.kernel.org>
Reported-by: Nico Huber <nico.h@gmx.de>
Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Julius Werner 2017-06-02 15:36:39 -07:00 committed by Greg Kroah-Hartman
parent cdc1daca1b
commit 32829da54d
1 changed files with 1 additions and 1 deletions
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2
drivers/char/mem.c
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@ -343,7 +343,7 @@ static int mmap_mem(struct file *file, struct vm_area_struct *vma)
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)
if (offset + (phys_addr_t)size - 1 < offset)
return -EINVAL;
if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))