drivers: char: mem: Check for address space wraparound with mmap()

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commit b299cde245 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>

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Julius Werner 2017-05-12 14:42:58 -07:00 • committed by Greg Kroah-Hartman

parent 51d9c51523

commit 1489183c20

1 changed files with 5 additions and 0 deletions

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drivers/char/mem.c

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