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Sat, 07 Nov 2026 03:17:24 -0800 (PST) Received: from kapoor.iiserb.ac.in ([203.18.51.239]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36fa9fd0000sm13284120eec.21.2026.11.07.03.17.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Nov 2026 03:17:24 -0800 (PST) From: Arnav Kapoor To: Jonathan Cameron Cc: David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko , Andy Shevchenko , Gwendal Grignou , Stephen Boyd , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Arnav Kapoor Subject: [PATCH 1/2] iio: proximity: sx9310: reject unsupported hardware gain values Date: Sat, 7 Nov 2026 16:47:03 +0530 Message-ID: <20261107111710.442318-2-kapoorarnav43@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107111710.442318-1-kapoorarnav43@gmail.com> References: <20261107111710.442318-1-kapoorarnav43@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit sx9310_write_gain() passes any value from userspace to ilog2() and then FIELD_PREP() into the 2-bit gain field without checking it. Only gains of 1, 2, 4 and 8 are supported (and listed in hardwaregain_available), but other values are not rejected; they are silently changed: - 3, 5, 6, 7 are rounded down to the next power of two; - 16 and larger wrap around in the 2-bit field, e.g. 16 sets a gain of 1 and 32 a gain of 2; - 0 and negative values set the maximum gain of 8, because ilog2(0) is -1 and a negative int becomes a large unsigned value. The write returns success in every case, so userspace cannot tell that the gain it asked for was not applied. Return -EINVAL for anything other than 1, 2, 4 or 8. Fixes: 227c83faa2f8 ("iio: sx9310: Support hardware gain factor") Signed-off-by: Arnav Kapoor --- drivers/iio/proximity/sx9310.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c index 2585b9c6fb69..27b5d604a409 100644 --- a/drivers/iio/proximity/sx9310.c +++ b/drivers/iio/proximity/sx9310.c @@ -665,6 +665,9 @@ static int sx9310_write_gain(struct sx_common_data *data, { unsigned int gain, mask; + if (val <= 0 || val > 8 || !is_power_of_2(val)) + return -EINVAL; + gain = ilog2(val); switch (chan->channel) { -- 2.53.0