Hi David,
On 11 April 2018 at 22:52, David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote:
> libfdt is never supposed to access memory outside the the blob, or outside
> the sub-blocks within it, even if the blob is badly corrupted.
>
> We can leverage valgrind's client requests to do better testing of this.
> This adds a vg_prepare_blob() function which marks just the valid parts of
> an fdt blob as properly initialized, explicitly marking the rest as
> uninitialized. This means valgrind should catch any bad accesses.
>
> We add a call to vg_prepare_blob() to load_blob() so that lots of the
> existing testcases will benefit from the extra checking.
>
> Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> ---
> tests/tests.h | 1 +
> tests/testutils.c | 52 +++++++++++++++++++++++++++++++++++++++++++++-
> tests/truncated_property.c | 2 ++
> tests/truncated_string.c | 2 ++
> 4 files changed, 56 insertions(+), 1 deletion(-)
>
Reviewed-by: Simon Glass <sjg@xxxxxxxxxxxx>
Please see below
[..]
> diff --git a/tests/testutils.c b/tests/testutils.c
> index d6d6818..ea8a022 100644
> --- a/tests/testutils.c
> +++ b/tests/testutils.c
> @@ -161,14 +161,64 @@ int nodename_eq(const char *s1, const char *s2)
> return 0;
> }
>
> +void vg_prepare_blob(void *fdt, size_t bufsize)
> +{
> + char *blob = fdt;
> + int off_memrsv, off_strings, off_struct;
> + size_t size_memrsv, size_strings, size_struct;
> +
> + size_memrsv = (fdt_num_mem_rsv(fdt) + 1)
> + * sizeof(struct fdt_reserve_entry);
> +
> + VALGRIND_MAKE_MEM_UNDEFINED(blob, bufsize);
> + VALGRIND_MAKE_MEM_DEFINED(blob, FDT_V1_SIZE);
> + VALGRIND_MAKE_MEM_DEFINED(blob, fdt_header_size(fdt));
> +
> + if (fdt_magic(fdt) == FDT_MAGIC) {
> + off_memrsv = fdt_off_mem_rsvmap(fdt);
> +
> + off_strings = fdt_off_dt_strings(fdt);
> + if (fdt_version(fdt) >= 3)
> + size_strings = fdt_size_dt_strings(fdt);
> + else
> + size_strings = fdt_totalsize(fdt) - off_strings;
> +
> + off_struct = fdt_off_dt_struct(fdt);
> + if (fdt_version(fdt) >= 17)
> + size_struct = fdt_size_dt_struct(fdt);
> + else
> + size_struct = fdt_totalsize(fdt) - off_struct;
> + } else if (fdt_magic(fdt) == (~FDT_MAGIC)) {
I suggest making ~FDT_MAGIC a separate constant (in another patch).
[..]
Regards,
Simon
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