metag/usercopy: Fix alignment error checking

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commit 2257211942 upstream.

Fix the error checking of the alignment adjustment code in
raw_copy_from_user(), which mistakenly considers it safe to skip the
error check when aligning the source buffer on a 2 or 4 byte boundary.

If the destination buffer was unaligned it may have started to copy
using byte or word accesses, which could well be at the start of a new
(valid) source page. This would result in it appearing to have copied 1
or 2 bytes at the end of the first (invalid) page rather than none at
all.

Fixes: 373cd784d0 ("metag: Memory handling")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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James Hogan 2017-03-31 11:23:18 +01:00 • committed by Greg Kroah-Hartman

parent 2bb52b47e7

commit 49a292dcd8

1 changed files with 4 additions and 6 deletions

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arch/metag/lib/usercopy.c

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