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SubjectRe: [PATCH] lib/mpi: Fix kernel unaligned acces in mpi_write_to_sgl
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On 04/21/2016 04:07 AM, Sowmini Varadhan wrote:
>
> Commit 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers") added
> mpi_write_to_sgl() which generates traps due to unaligned
> access on some platforms like sparc. Fix this by using
> the get_unaligned* and put_unaligned* functions.
>
> Fixes: 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers")
> Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
> ---
> lib/mpi/mpicoder.c | 12 ++++++++----
> 1 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
> index eb15e7d..6771378 100644
> --- a/lib/mpi/mpicoder.c
> +++ b/lib/mpi/mpicoder.c
> @@ -21,6 +21,7 @@
> #include <linux/bitops.h>
> #include <linux/count_zeros.h>
> #include "mpi-internal.h"
> +#include <asm/unaligned.h>
>
> #define MAX_EXTERN_MPI_BITS 16384
>
> @@ -405,10 +406,13 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
> p -= sizeof(alimb);
> continue;
> } else {
> - mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
> - mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
> - + lzeros;
> - *limb1 = *limb2;
> + mpi_limb_t tmp;
> +
> + tmp = get_unaligned_be32((void *)p -
> + sizeof(alimb) +
> + lzeros);
> + put_unaligned_be32(tmp,
> + (void *)p - sizeof(alimb));
> p -= lzeros;
> y = lzeros;
> }

What if the mpi_limb_t will happen to be 64 bit?
Thanks,
--
TS

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