From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Cc: Kees Cook <keescook@chromium.org>,
linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-hardening@vger.kernel.org
Subject: [PATCH 2/2][next] clk: visconti: Add bounds-checking coverage for struct visconti_pll_provider
Date: Wed, 11 Oct 2023 20:18:45 -0600 [thread overview]
Message-ID: <675633f7ae9893371d35b238f06fd02a3acffebb.1697076650.git.gustavoars@kernel.org> (raw)
In-Reply-To: <cover.1697076650.git.gustavoars@kernel.org>
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 f316cdff8d67 ("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. :)
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/clk/visconti/pll.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/clk/visconti/pll.c b/drivers/clk/visconti/pll.c
index 1f3234f22667..e9cd80e085dc 100644
--- a/drivers/clk/visconti/pll.c
+++ b/drivers/clk/visconti/pll.c
@@ -329,12 +329,12 @@ struct visconti_pll_provider * __init visconti_init_pll(struct device_node *np,
if (!ctx)
return ERR_PTR(-ENOMEM);
- for (i = 0; i < nr_plls; ++i)
- ctx->clk_data.hws[i] = ERR_PTR(-ENOENT);
-
ctx->node = np;
ctx->reg_base = base;
ctx->clk_data.num = nr_plls;
+ for (i = 0; i < nr_plls; ++i)
+ ctx->clk_data.hws[i] = ERR_PTR(-ENOENT);
+
return ctx;
}
--
2.34.1
next prev parent reply other threads:[~2023-10-12 2:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-12 2:14 [PATCH 0/2][next] clk: visconti: Fix undefined behavior bug and add bounds-checking coverage Gustavo A. R. Silva
2023-10-12 2:17 ` [PATCH 1/2][next] clk: visconti: Fix undefined behavior bug in struct visconti_pll_provider Gustavo A. R. Silva
2023-10-12 16:21 ` Kees Cook
2023-10-15 22:49 ` nobuhiro1.iwamatsu
2023-10-12 2:18 ` Gustavo A. R. Silva [this message]
2023-10-12 16:21 ` [PATCH 2/2][next] clk: visconti: Add bounds-checking coverage for " Kees Cook
2023-10-15 22:50 ` nobuhiro1.iwamatsu
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