On Wed, Oct 05, 2022 at 04:29:31PM -0700, Tadeusz Struk wrote:
> Add a new test get_next_tag_invalid_prop_len, which covers
> fdt_next_tag(), when it is passed an corrupted blob, with
> invalid property len values.
>
> Signed-off-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxxx>
Looks good overall, but a bunch of minor things to polish.
> ---
> tests/.gitignore | 1 +
> tests/Makefile.tests | 2 +-
> tests/get_next_tag_invalid_prop_len.c | 84 +++++++++++++++++++++++++++
> tests/meson.build | 1 +
> tests/run_tests.sh | 1 +
> 5 files changed, 88 insertions(+), 1 deletion(-)
> create mode 100644 tests/get_next_tag_invalid_prop_len.c
>
> diff --git a/tests/.gitignore b/tests/.gitignore
> index 03bdde2..3376ed9 100644
> --- a/tests/.gitignore
> +++ b/tests/.gitignore
> @@ -74,3 +74,4 @@ tmp.*
> /truncated_memrsv
> /utilfdt_test
> /value-labels
> +/get_next_tag_invalid_prop_len
> diff --git a/tests/Makefile.tests b/tests/Makefile.tests
> index 2d36c5d..2c5b4c9 100644
> --- a/tests/Makefile.tests
> +++ b/tests/Makefile.tests
> @@ -4,7 +4,7 @@ LIB_TESTS_L = get_mem_rsv \
> get_path supernode_atdepth_offset parent_offset \
> node_offset_by_prop_value node_offset_by_phandle \
> node_check_compatible node_offset_by_compatible \
> - get_alias \
> + get_alias get_next_tag_invalid_prop_len \
> char_literal \
> sized_cells \
> notfound \
> diff --git a/tests/get_next_tag_invalid_prop_len.c b/tests/get_next_tag_invalid_prop_len.c
> new file mode 100644
> index 0000000..f5a6d99
> --- /dev/null
> +++ b/tests/get_next_tag_invalid_prop_len.c
> @@ -0,0 +1,84 @@
> +// SPDX-License-Identifier: LGPL-2.1-or-later
> +/*
> + * libfdt - Flat Device Tree manipulation
> + * Testcase for fdt_next_tag()
> + */
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdint.h>
> +
> +#include <libfdt.h>
> +#include "tests.h"
> +#include "testdata.h"
> +
> +#define FDT_SIZE 65536
> +#define CHECK_ERR(err) \
> +({ if (err) { \
> + free(fdt); \
You don't need the free() here, you're about to quit the test program
anyway.
> + FAIL("%s: %d: %s", __FILE__, __LINE__, fdt_strerror(err)); \
> + } \
> +})
> +
> +int main(int argc, char *argv[])
> +{
> + struct fdt_property *prp;
> + void *fdt;
> + int nextoff = 0, offset, err;
> + uint32_t tag, val;
> +
> + test_init(argc, argv);
> + fdt = calloc(1, FDT_SIZE);
No need to use cleared memory, the fdt_sw functions will work just
fine with an uninitialized buffer.
> + if (!fdt)
> + FAIL("Can't allocate memory");
> + err = fdt_create(fdt, FDT_SIZE);
> + CHECK_ERR(err);
> + err = fdt_add_reservemap_entry(fdt, 0xdeadbeefUL, 0x10000UL);
No need to insert a dummy reservemap entry here.
> + CHECK_ERR(err);
> + err = fdt_finish_reservemap(fdt);
> + CHECK_ERR(err);
> + err = fdt_begin_node(fdt, "");
> + CHECK_ERR(err);
> + err = fdt_begin_node(fdt, "subnode1");
> + CHECK_ERR(err);
No particular need for this subnode either, you can test what you want
with properties on the root node.
> + err = fdt_property_u32(fdt, "prop-int-32", 0x1234);
> + CHECK_ERR(err);
> + err = fdt_property_u32(fdt, "prop2-int-32", 0x4321);
> + CHECK_ERR(err);
> + err = fdt_end_node(fdt);
> + CHECK_ERR(err);
> + err = fdt_end_node(fdt);
> + CHECK_ERR(err);
> + offset = -1;
> + val = cpu_to_fdt32(0x1234);
> + offset = fdt_node_offset_by_prop_value(fdt, offset, "prop-int-32",
> + &val, sizeof(val));
fdt_node_offset_by_prop_value() is a very roundabout way to find the
node you need - you know the path (and if you get rid of the
unnecessary subnode, it'll just be the root node at offset 0).
> + do {
> + tag = fdt_next_tag(fdt, offset, &nextoff);
> + offset = nextoff;
> + } while (tag != FDT_PROP);
> +
> + /* Calculate len to property */
> + prp = (struct fdt_property *)(((char*)fdt) + fdt_off_dt_struct(fdt) + offset);
You could replace the loop as well as this nasty pointer arithmetic
with an fdt_get_property_w() call.
> + /* int overflow case */
Probably worth testing the fdt_next_tag() behaviour on the unmangled
tree before testing the corrupted cases. If the test ever breaks,
that sort of thing makes it easier to figure out if the breakage is in
the library, or the testcase.
> + prp->len = cpu_to_fdt32(0xFFFFFFFA);
> + tag = fdt_next_tag(fdt, offset, &nextoff);
> + if (tag != FDT_END)
> + FAIL("Invalid tag %x, expected premature end", tag);
> +
> + if (nextoff != -FDT_ERR_BADSTRUCTURE)
> + FAIL("Invalid nextoff, expected error -FDT_ERR_BADSTRUCTURE");
> +
> + /* negative offset case */
> + prp->len = cpu_to_fdt32(0x7FFFFFFA);
> + tag = fdt_next_tag(fdt, offset, &nextoff);
> + if (tag != FDT_END)
> + FAIL("Invalid tag, expected premature end");
> +
> + if (nextoff != -FDT_ERR_BADSTRUCTURE)
> + FAIL("Invalid nextoff, expected error -FDT_ERR_BADSTRUCTURE");
> +
> + free(fdt);
> + PASS();
> +}
> diff --git a/tests/meson.build b/tests/meson.build
<> index 4ac154a..29a42dd 100644
> --- a/tests/meson.build
> +++ b/tests/meson.build
> @@ -47,6 +47,7 @@ tests = [
> 'get_path',
> 'get_phandle',
> 'get_prop_offset',
> + 'get_next_tag_invalid_prop_len',
> 'getprop',
> 'incbin',
> 'integer-expressions',
> diff --git a/tests/run_tests.sh b/tests/run_tests.sh
> index 244df8a..46678cb 100755
> --- a/tests/run_tests.sh
> +++ b/tests/run_tests.sh
> @@ -513,6 +513,7 @@ libfdt_tests () {
> run_dtc_test -I fs -O dts -o fs.test_tree1.test.dts $FSBASE/test_tree1
> run_dtc_test -I fs -O dtb -o fs.test_tree1.test.dtb $FSBASE/test_tree1
> run_test dtbs_equal_unordered -m fs.test_tree1.test.dtb test_tree1.dtb
> + run_test get_next_tag_invalid_prop_len
>
> ## https://github.com/dgibson/dtc/issues/64
> check_tests "$SRCDIR/phandle-args-overflow.dts" clocks_property
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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