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| author | Babanpreet Singh <bbnpreetsingh@gmail.com> | 2026-07-14 04:29:10 +0000 |
|---|---|---|
| committer | William Breathitt Gray <wbg@kernel.org> | 2026-08-02 21:41:51 +0900 |
| commit | f1a3a9946aab611dd2200c01ff122f64b033dad2 (patch) | |
| tree | 8fcb8d57ea9f6d0ebefd9ded721599f56bbfbc2f | |
| parent | dc59e4fea9d83f03bad6bddf3fa2e52491777482 (diff) | |
| download | linux-next-f1a3a9946aab611dd2200c01ff122f64b033dad2.tar.gz linux-next-f1a3a9946aab611dd2200c01ff122f64b033dad2.zip | |
counter: microchip-tcb-capture: Fix DT channel validation
mchp_tc_probe() reads the devicetree "reg" cell - a u32, per the API
contract of of_property_read_u32_index() - into a signed int, so the
bounds check "channel > 2" fails to reject cell values at or above
0x80000000: reinterpreted as a negative int, they compare below 2 and
pass validation.
A malformed devicetree can therefore drive a negative channel into the
ATMEL_TC_REG() offset arithmetic, making the driver access syscon
regmap offsets outside the TC block's register window, and into the
"t%d_clk" clock-name formatting, where it truncates clk_name (sized
for "t0_clk".."t2_clk").
Declare channel as u32, matching the API contract; the unsigned
comparison then rejects everything except channels 0..2. Adjust the
format specifier to %u accordingly, which also resolves the W=1
warning that exposed the gap:
microchip-tcb-capture.c:520:56: warning: '%d' directive output may
be truncated writing between 1 and 11 bytes into a region of size
6 [-Wformat-truncation=]
note: directive argument in the range [-2147483648, 2]
No behavior change for well-formed devicetrees: channels 0..2 take
identical paths before and after.
Fixes: 106b104137fd ("counter: Add microchip TCB capture counter")
Assisted-by: Claude:claude-fable-5 [gcc W=1]
Signed-off-by: Babanpreet Singh <bbnpreetsingh@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Link: https://lore.kernel.org/r/20260714042910.7-1-bbnpreetsingh@gmail.com
Signed-off-by: William Breathitt Gray <wbg@kernel.org>
| -rw-r--r-- | drivers/counter/microchip-tcb-capture.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/counter/microchip-tcb-capture.c b/drivers/counter/microchip-tcb-capture.c index 19d457ae4c3b..e53a8390756b 100644 --- a/drivers/counter/microchip-tcb-capture.c +++ b/drivers/counter/microchip-tcb-capture.c @@ -483,7 +483,7 @@ static int mchp_tc_probe(struct platform_device *pdev) char clk_name[7]; struct regmap *regmap; struct clk *clk[3]; - int channel; + u32 channel; int ret, i; counter = devm_counter_alloc(&pdev->dev, sizeof(*priv)); @@ -517,7 +517,7 @@ static int mchp_tc_probe(struct platform_device *pdev) priv->channel[i] = channel; - snprintf(clk_name, sizeof(clk_name), "t%d_clk", channel); + snprintf(clk_name, sizeof(clk_name), "t%u_clk", channel); clk[i] = of_clk_get_by_name(np->parent, clk_name); if (IS_ERR(clk[i])) { |