Messages in this thread Patch in this message | | | Date | Mon, 25 Jun 2018 15:23:16 -0700 | From | Kees Cook <> | Subject | [PATCH v2] usb: typec: tps6598x: Remove VLA usage |
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In the quest to remove all stack VLA usage from the kernel[1], this uses the maximum buffer size and adds a sanity check. While 25 bytes is the size of the largest current things coming through, Heikki Krogerus pointed out that the actual max in 64 bytes, as per ch 1.3.2 http://www.ti.com/lit/ug/slvuan1a/slvuan1a.pdf
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org> --- v2: use 64 bytes (Heikki) --- drivers/usb/typec/tps6598x.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/typec/tps6598x.c b/drivers/usb/typec/tps6598x.c index 4b4c8d271b27..c84c8c189e90 100644 --- a/drivers/usb/typec/tps6598x.c +++ b/drivers/usb/typec/tps6598x.c @@ -81,12 +81,21 @@ struct tps6598x { struct typec_capability typec_cap; }; +/* + * Max data bytes for Data1, Data2, and other registers. See ch 1.3.2: + * http://www.ti.com/lit/ug/slvuan1a/slvuan1a.pdf + */ +#define TPS_MAX_LEN 64 + static int tps6598x_block_read(struct tps6598x *tps, u8 reg, void *val, size_t len) { - u8 data[len + 1]; + u8 data[TPS_MAX_LEN + 1]; int ret; + if (WARN_ON(len + 1 > sizeof(data))) + return -EINVAL; + if (!tps->i2c_protocol) return regmap_raw_read(tps->regmap, reg, val, len); -- 2.17.1
-- Kees Cook Pixel Security
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