From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Jean Delvare <jdelvare@suse.com>,
Guenter Roeck <linux@roeck-us.net>, Joel Stanley <joel@jms.id.au>,
Andrew Jeffery <andrew@codeconstruct.com.au>
Cc: linux-hwmon@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-hardening@vger.kernel.org
Subject: [PATCH v2][next] hwmon: (aspeed-pwm-tacho) Fix -Wstringop-overflow warning in aspeed_create_fan_tach_channel()
Date: Tue, 14 Nov 2023 13:53:08 -0600 [thread overview]
Message-ID: <ZVPQJIP26dIzRAr6@work> (raw)
Based on the documentation below, the maximum number of Fan tach
channels is 16:
Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt:45:
45 - aspeed,fan-tach-ch : should specify the Fan tach input channel.
46 integer value in the range 0 through 15, with 0 indicating
47 Fan tach channel 0 and 15 indicating Fan tach channel 15.
48 At least one Fan tach input channel is required.
However, the compiler doesn't know that, and legitimaly warns about a potential
overwrite in array `u8 fan_tach_ch_source[16]` in `struct aspeed_pwm_tacho_data`,
in case `index` takes a value outside the boundaries of the array:
drivers/hwmon/aspeed-pwm-tacho.c:
179 struct aspeed_pwm_tacho_data {
...
184 bool fan_tach_present[16];
...
193 u8 fan_tach_ch_source[16];
196 };
In function ‘aspeed_create_fan_tach_channel’,
inlined from ‘aspeed_create_fan’ at drivers/hwmon/aspeed-pwm-tacho.c:877:2,
inlined from ‘aspeed_pwm_tacho_probe’ at drivers/hwmon/aspeed-pwm-tacho.c:936:9:
drivers/hwmon/aspeed-pwm-tacho.c:751:49: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
751 | priv->fan_tach_ch_source[index] = pwm_source;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
drivers/hwmon/aspeed-pwm-tacho.c: In function ‘aspeed_pwm_tacho_probe’:
drivers/hwmon/aspeed-pwm-tacho.c:193:12: note: at offset [48, 255] into destination object ‘fan_tach_ch_source’ of size 16
193 | u8 fan_tach_ch_source[16];
| ^~~~~~~~~~~~~~~~~~
Fix this by sanity checking `index` before using it to index arrays of
size 16 elements in `struct aspeed_pwm_tacho_data`. Also, pass `dev` as
argument to function `aspeed_create_fan_tach_channel()`, and add an error
message in case `index` is out-of-bounds, in which case return `-EINVAL`.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
Changes in v2:
- Pass `dev` to function aspeed_create_fan_tach_channel() and return
-EINVAL in case of error. (Guenter)
- Update changelog text.
v1:
- Link: https://lore.kernel.org/linux-hardening/ZVJ7JBFoULzY3VGx@work/
drivers/hwmon/aspeed-pwm-tacho.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c
index 997df4b40509..9a209e064e46 100644
--- a/drivers/hwmon/aspeed-pwm-tacho.c
+++ b/drivers/hwmon/aspeed-pwm-tacho.c
@@ -166,6 +166,8 @@
#define MAX_CDEV_NAME_LEN 16
+#define MAX_ASPEED_FAN_TACH_CHANNELS 16
+
struct aspeed_cooling_device {
char name[16];
struct aspeed_pwm_tacho_data *priv;
@@ -181,7 +183,7 @@ struct aspeed_pwm_tacho_data {
struct reset_control *rst;
unsigned long clk_freq;
bool pwm_present[8];
- bool fan_tach_present[16];
+ bool fan_tach_present[MAX_ASPEED_FAN_TACH_CHANNELS];
u8 type_pwm_clock_unit[3];
u8 type_pwm_clock_division_h[3];
u8 type_pwm_clock_division_l[3];
@@ -190,7 +192,7 @@ struct aspeed_pwm_tacho_data {
u16 type_fan_tach_unit[3];
u8 pwm_port_type[8];
u8 pwm_port_fan_ctrl[8];
- u8 fan_tach_ch_source[16];
+ u8 fan_tach_ch_source[MAX_ASPEED_FAN_TACH_CHANNELS];
struct aspeed_cooling_device *cdev[8];
const struct attribute_group *groups[3];
};
@@ -737,7 +739,8 @@ static void aspeed_create_pwm_port(struct aspeed_pwm_tacho_data *priv,
aspeed_set_pwm_port_fan_ctrl(priv, pwm_port, INIT_FAN_CTRL);
}
-static void aspeed_create_fan_tach_channel(struct aspeed_pwm_tacho_data *priv,
+static int aspeed_create_fan_tach_channel(struct device *dev,
+ struct aspeed_pwm_tacho_data *priv,
u8 *fan_tach_ch,
int count,
u8 pwm_source)
@@ -746,11 +749,17 @@ static void aspeed_create_fan_tach_channel(struct aspeed_pwm_tacho_data *priv,
for (val = 0; val < count; val++) {
index = fan_tach_ch[val];
+ if (index >= MAX_ASPEED_FAN_TACH_CHANNELS) {
+ dev_err(dev, "Invalid Fan Tach input channel %u\n.", index);
+ return -EINVAL;
+ }
aspeed_set_fan_tach_ch_enable(priv->regmap, index, true);
priv->fan_tach_present[index] = true;
priv->fan_tach_ch_source[index] = pwm_source;
aspeed_set_fan_tach_ch_source(priv->regmap, index, pwm_source);
}
+
+ return 0;
}
static int
@@ -874,7 +883,10 @@ static int aspeed_create_fan(struct device *dev,
fan_tach_ch, count);
if (ret)
return ret;
- aspeed_create_fan_tach_channel(priv, fan_tach_ch, count, pwm_port);
+
+ ret = aspeed_create_fan_tach_channel(dev, priv, fan_tach_ch, count, pwm_port);
+ if (ret)
+ return ret;
return 0;
}
--
2.34.1
next reply other threads:[~2023-11-14 19:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-14 19:53 Gustavo A. R. Silva [this message]
2023-11-15 3:03 ` [PATCH v2][next] hwmon: (aspeed-pwm-tacho) Fix -Wstringop-overflow warning in aspeed_create_fan_tach_channel() Kees Cook
2023-11-15 13:12 ` Guenter Roeck
2023-11-15 18:03 ` Gustavo A. R. Silva
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZVPQJIP26dIzRAr6@work \
--to=gustavoars@kernel.org \
--cc=andrew@codeconstruct.com.au \
--cc=jdelvare@suse.com \
--cc=joel@jms.id.au \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-aspeed@lists.ozlabs.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-hwmon@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@roeck-us.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).