In order to gain the bounds-checking coverage that __counted_by provides
to flexible-array members at run-time via CONFIG_UBSAN_BOUNDS (for array
indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions),
we must make sure that the counter member, in this particular case `num`,
is updated before the first access to the flex-array member, in this
particular case array `hws`. See below:
commit f316cdff8d ("clk: Annotate struct clk_hw_onecell_data with
__counted_by") introduced `__counted_by` for `struct clk_hw_onecell_data`
together with changes to relocate some of assignments of counter `num`
before `hws` is accessed:
include/linux/clk-provider.h:
1380 struct clk_hw_onecell_data {
1381 unsigned int num;
1382 struct clk_hw *hws[] __counted_by(num);
1383 };
However, this structure is used as a member in other structs, in this
case in `struct visconti_pll_provider`:
drivers/clk/visconti/pll.h:
16 struct visconti_pll_provider {
17 void __iomem *reg_base;
18 struct device_node *node;
19
20 /* Must be last */
21 struct clk_hw_onecell_data clk_data;
22 };
Hence, we need to move the assignments to `ctx->clk_data.num` after
allocation for `struct visconti_pll_provider` and before accessing the
flexible array `ctx->clk_data.hws`. And, as assignments for all members
in `struct visconti_pll_provider` are originally adjacent to each other,
relocate all assignments together, so we don't split up
`ctx->clk_data.hws = nr_plls` from the rest. :)
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/e3189f3e40e8723b6d794fb2260e2e9ab6b960bd.1697492890.git.gustavoars@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
397d887c16