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 <[email protected]>
---
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..f5ba23f0fed5 100644
--- a/drivers/hwmon/pmbus/max20730.c
+++ b/drivers/hwmon/pmbus/max20730.c
@@ -113,7 +113,8 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
struct max20730_debugfs_data *psu = to_psu(idxp, idx);
const struct pmbus_driver_info *info;
const struct max20730_data *data;
- char tbuf[DEBUG_FS_DATA_MAX] = { 0 };
+ char tbuf[DEBUG_FS_DATA_MAX] = {};
+ 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)
@@ -287,9 +288,10 @@ 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";
}
+ len = strlen(result);
return simple_read_from_buffer(buf, count, ppos, tbuf, len);
}
--
2.41.0.255.g8b1d071c50-goog
On 7/12/23 07:44, Azeem Shaikh wrote:
> 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 <[email protected]>
> ---
> 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..f5ba23f0fed5 100644
> --- a/drivers/hwmon/pmbus/max20730.c
> +++ b/drivers/hwmon/pmbus/max20730.c
> @@ -113,7 +113,8 @@ static ssize_t max20730_debugfs_read(struct file *file, char __user *buf,
> struct max20730_debugfs_data *psu = to_psu(idxp, idx);
> const struct pmbus_driver_info *info;
> const struct max20730_data *data;
> - char tbuf[DEBUG_FS_DATA_MAX] = { 0 };
> + char tbuf[DEBUG_FS_DATA_MAX] = {};
Unrelated change.
> + 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)
> @@ -287,9 +288,10 @@ 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";
> }
>
> + len = strlen(result);
> return simple_read_from_buffer(buf, count, ppos, tbuf, len);
This still copies tbuf, meaning all those constant strings won't actually
be reported.
> }
>
> --
> 2.41.0.255.g8b1d071c50-goog
>
>
On 7/12/23 07:44, Azeem Shaikh wrote:
> 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 <[email protected]>
Also, $subject should include the affected driver.
Guenter
On Wed, Jul 12, 2023 at 08:16:39AM -0700, Guenter Roeck wrote:
> On 7/12/23 07:44, Azeem Shaikh wrote:
> > [...]
> > + len = strlen(result);
> > return simple_read_from_buffer(buf, count, ppos, tbuf, len);
>
> This still copies tbuf, meaning all those constant strings won't actually
> be reported.
Ah dang, thanks for catching that. Yeah, "tbuf" should be replaced by
"result" in the simple_read_from_buffer().
--
Kees Cook
On Wed, Jul 12, 2023 at 2:04 PM Kees Cook <[email protected]> wrote:
>
> On Wed, Jul 12, 2023 at 08:16:39AM -0700, Guenter Roeck wrote:
> > On 7/12/23 07:44, Azeem Shaikh wrote:
> > > [...]
> > > + len = strlen(result);
> > > return simple_read_from_buffer(buf, count, ppos, tbuf, len);
> >
> > This still copies tbuf, meaning all those constant strings won't actually
> > be reported.
>
> Ah dang, thanks for catching that. Yeah, "tbuf" should be replaced by
> "result" in the simple_read_from_buffer().
>
Thanks for review folks, will send out a v2 shortly.