Re: [RESEND 2][PATCH v4] hexdump: fix for non-aligned buffers

Joe Perches
2015-07-08T23:49:17Z

On Thu, 2015-07-09 at 01:44 +0200, Horacio Mijail Antón Quiles wrote:
> An hexdump with a buf not aligned to the groupsize causes
> non-naturally-aligned memory accesses. This was causing a kernel panic on
> the processor BlackFin BF527, when such an unaligned buffer was fed by the
> function ubifs_scanned_corruption in fs/ubifs/scan.c .

Seems sensible enough to me.

> ---
> diff --git a/lib/hexdump.c b/lib/hexdump.c
[]
> @@ -124,6 +124,11 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize,
> if ((len % groupsize) != 0) /* no mixed size output */
> groupsize = 1;
>
> + /* fall back to 1-byte groups if buf is not aligned to groupsize */
> + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) &&
> + !IS_ALIGNED((uintptr_t)buf, groupsize))
> + groupsize = 1;
> +
> ngroups = len / groupsize;
> ascii_column = rowsize * 2 + rowsize / groupsize + 1;
>