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Date: Wed, 12 Jul 2023 21:43:07 +0000
From: Azeem Shaikh <azeemshaikh38@...il.com>
To: Guenter Roeck <linux@...ck-us.net>,
Kees Cook <keescook@...omium.org>
Cc: linux-hardening@...r.kernel.org,
Azeem Shaikh <azeemshaikh38@...il.com>,
linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
Jean Delvare <jdelvare@...e.com>
Subject: [PATCH v2] hwmon: (pmbus/max20730) Remove strlcpy occurences
strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with direct assignment.
strlcpy in this file is used to copy fixed-length strings which can be
completely avoided by direct assignment and is safe to do so. strlen()
is used to return the length of @tbuf.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
---
v2:
* Includes driver name in commit header.
* Removes unrelated change tbuf{ 0 } -> tbuf{}.
* Fixes bug where @tbuf was being passed instead of @result.
v1:
* https://lore.kernel.org/all/20230712144429.2845940-1-azeemshaikh38@gmail.com/
drivers/hwmon/pmbus/max20730.c | 64 +++++++++++++++++++++--------------------
1 file changed, 33 insertions(+), 31 deletions(-)
diff --git a/drivers/hwmon/pmbus/max20730.c b/drivers/hwmon/pmbus/max20730.c
index 7bcf27995033..1de34da177c9 100644
--- a/drivers/hwmon/pmbus/max20730.c
+++ b/drivers/hwmon/pmbus/max20730.c
@@ -114,6 +114,7 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
const struct pmbus_driver_info *info;
const struct max20730_data *data;
char tbuf[DEBUG_FS_DATA_MAX] = { 0 };
+ char *result = tbuf;
u16 val;
info = pmbus_get_driver_info(psu->client);
@@ -148,13 +149,13 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
>> MAX20730_MFR_DEVSET1_TSTAT_BIT_POS;
if (val == 0)
- len = strlcpy(tbuf, "2000\n", DEBUG_FS_DATA_MAX);
+ result = "2000\n";
else if (val == 1)
- len = strlcpy(tbuf, "125\n", DEBUG_FS_DATA_MAX);
+ result = "125\n";
else if (val == 2)
- len = strlcpy(tbuf, "62.5\n", DEBUG_FS_DATA_MAX);
+ result = "62.5\n";
else
- len = strlcpy(tbuf, "32\n", DEBUG_FS_DATA_MAX);
+ result = "32\n";
break;
case MAX20730_DEBUGFS_INTERNAL_GAIN:
val = (data->mfr_devset1 & MAX20730_MFR_DEVSET1_RGAIN_MASK)
@@ -163,35 +164,35 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
if (data->id == max20734) {
/* AN6209 */
if (val == 0)
- len = strlcpy(tbuf, "0.8\n", DEBUG_FS_DATA_MAX);
+ result = "0.8\n";
else if (val == 1)
- len = strlcpy(tbuf, "3.2\n", DEBUG_FS_DATA_MAX);
+ result = "3.2\n";
else if (val == 2)
- len = strlcpy(tbuf, "1.6\n", DEBUG_FS_DATA_MAX);
+ result = "1.6\n";
else
- len = strlcpy(tbuf, "6.4\n", DEBUG_FS_DATA_MAX);
+ result = "6.4\n";
} else if (data->id == max20730 || data->id == max20710) {
/* AN6042 or AN6140 */
if (val == 0)
- len = strlcpy(tbuf, "0.9\n", DEBUG_FS_DATA_MAX);
+ result = "0.9\n";
else if (val == 1)
- len = strlcpy(tbuf, "3.6\n", DEBUG_FS_DATA_MAX);
+ result = "3.6\n";
else if (val == 2)
- len = strlcpy(tbuf, "1.8\n", DEBUG_FS_DATA_MAX);
+ result = "1.8\n";
else
- len = strlcpy(tbuf, "7.2\n", DEBUG_FS_DATA_MAX);
+ result = "7.2\n";
} else if (data->id == max20743) {
/* AN6042 */
if (val == 0)
- len = strlcpy(tbuf, "0.45\n", DEBUG_FS_DATA_MAX);
+ result = "0.45\n";
else if (val == 1)
- len = strlcpy(tbuf, "1.8\n", DEBUG_FS_DATA_MAX);
+ result = "1.8\n";
else if (val == 2)
- len = strlcpy(tbuf, "0.9\n", DEBUG_FS_DATA_MAX);
+ result = "0.9\n";
else
- len = strlcpy(tbuf, "3.6\n", DEBUG_FS_DATA_MAX);
+ result = "3.6\n";
} else {
- len = strlcpy(tbuf, "Not supported\n", DEBUG_FS_DATA_MAX);
+ result = "Not supported\n";
}
break;
case MAX20730_DEBUGFS_BOOT_VOLTAGE:
@@ -199,26 +200,26 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
>> MAX20730_MFR_DEVSET1_VBOOT_BIT_POS;
if (val == 0)
- len = strlcpy(tbuf, "0.6484\n", DEBUG_FS_DATA_MAX);
+ result = "0.6484\n";
else if (val == 1)
- len = strlcpy(tbuf, "0.8984\n", DEBUG_FS_DATA_MAX);
+ result = "0.8984\n";
else if (val == 2)
- len = strlcpy(tbuf, "1.0\n", DEBUG_FS_DATA_MAX);
+ result = "1.0\n";
else
- len = strlcpy(tbuf, "Invalid\n", DEBUG_FS_DATA_MAX);
+ result = "Invalid\n";
break;
case MAX20730_DEBUGFS_OUT_V_RAMP_RATE:
val = (data->mfr_devset2 & MAX20730_MFR_DEVSET2_VRATE)
>> MAX20730_MFR_DEVSET2_VRATE_BIT_POS;
if (val == 0)
- len = strlcpy(tbuf, "4\n", DEBUG_FS_DATA_MAX);
+ result = "4\n";
else if (val == 1)
- len = strlcpy(tbuf, "2\n", DEBUG_FS_DATA_MAX);
+ result = "2\n";
else if (val == 2)
- len = strlcpy(tbuf, "1\n", DEBUG_FS_DATA_MAX);
+ result = "1\n";
else
- len = strlcpy(tbuf, "Invalid\n", DEBUG_FS_DATA_MAX);
+ result = "Invalid\n";
break;
case MAX20730_DEBUGFS_OC_PROTECT_MODE:
ret = (data->mfr_devset2 & MAX20730_MFR_DEVSET2_OCPM_MASK)
@@ -230,13 +231,13 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
>> MAX20730_MFR_DEVSET2_SS_BIT_POS;
if (val == 0)
- len = strlcpy(tbuf, "0.75\n", DEBUG_FS_DATA_MAX);
+ result = "0.75\n";
else if (val == 1)
- len = strlcpy(tbuf, "1.5\n", DEBUG_FS_DATA_MAX);
+ result = "1.5\n";
else if (val == 2)
- len = strlcpy(tbuf, "3\n", DEBUG_FS_DATA_MAX);
+ result = "3\n";
else
- len = strlcpy(tbuf, "6\n", DEBUG_FS_DATA_MAX);
+ result = "6\n";
break;
case MAX20730_DEBUGFS_IMAX:
ret = (data->mfr_devset2 & MAX20730_MFR_DEVSET2_IMAX_MASK)
@@ -287,10 +288,11 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
"%d.%d\n", ret / 10000, ret % 10000);
break;
default:
- len = strlcpy(tbuf, "Invalid\n", DEBUG_FS_DATA_MAX);
+ result = "Invalid\n";
}
- return simple_read_from_buffer(buf, count, ppos, tbuf, len);
+ len = strlen(result);
+ return simple_read_from_buffer(buf, count, ppos, result, len);
}
static const struct file_operations max20730_fops = {
--
2.41.0.255.g8b1d071c50-goog
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