`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
ethtool_sprintf() is designed specifically for get_strings() usage.
Let's replace strncpy in favor of this more robust and easier to
understand interface.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested only.
---
drivers/net/dsa/realtek/rtl8365mb.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/net/dsa/realtek/rtl8365mb.c b/drivers/net/dsa/realtek/rtl8365mb.c
index 41ea3b5a42b1..d171c18dd354 100644
--- a/drivers/net/dsa/realtek/rtl8365mb.c
+++ b/drivers/net/dsa/realtek/rtl8365mb.c
@@ -1303,8 +1303,7 @@ static void rtl8365mb_get_strings(struct dsa_switch *ds, int port, u32 stringset
for (i = 0; i < RTL8365MB_MIB_END; i++) {
struct rtl8365mb_mib_counter *mib = &rtl8365mb_mib_counters[i];
-
- strncpy(data + i * ETH_GSTRING_LEN, mib->name, ETH_GSTRING_LEN);
+ ethtool_sprintf(&data, "%s", mib->name);
}
}
---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231009-strncpy-drivers-net-dsa-realtek-rtl8365mb-c-bb106e4c110c
Best regards,
--
Justin Stitt <[email protected]>
On 10/9/23 15:43, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy in favor of this more robust and easier to
> understand interface.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
Reviewed-by: Florian Fainelli <[email protected]>
--
Florian
On Mon, Oct 09, 2023 at 10:43:59PM +0000, Justin Stitt wrote:
> [You don't often get email from [email protected]. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> `strncpy` is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy in favor of this more robust and easier to
> understand interface.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
Reviewed-by: Alvin Šipraga <[email protected]>
> ---
> Note: build-tested only.
> ---
> drivers/net/dsa/realtek/rtl8365mb.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/net/dsa/realtek/rtl8365mb.c b/drivers/net/dsa/realtek/rtl8365mb.c
> index 41ea3b5a42b1..d171c18dd354 100644
> --- a/drivers/net/dsa/realtek/rtl8365mb.c
> +++ b/drivers/net/dsa/realtek/rtl8365mb.c
> @@ -1303,8 +1303,7 @@ static void rtl8365mb_get_strings(struct dsa_switch *ds, int port, u32 stringset
>
> for (i = 0; i < RTL8365MB_MIB_END; i++) {
> struct rtl8365mb_mib_counter *mib = &rtl8365mb_mib_counters[i];
> -
> - strncpy(data + i * ETH_GSTRING_LEN, mib->name, ETH_GSTRING_LEN);
> + ethtool_sprintf(&data, "%s", mib->name);
> }
> }
>
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id: 20231009-strncpy-drivers-net-dsa-realtek-rtl8365mb-c-bb106e4c110c
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>
Hello Justin,
On Mon, Oct 09, 2023 at 10:43:59PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy in favor of this more robust and easier to
> understand interface.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested only.
> ---
> drivers/net/dsa/realtek/rtl8365mb.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/net/dsa/realtek/rtl8365mb.c b/drivers/net/dsa/realtek/rtl8365mb.c
> index 41ea3b5a42b1..d171c18dd354 100644
> --- a/drivers/net/dsa/realtek/rtl8365mb.c
> +++ b/drivers/net/dsa/realtek/rtl8365mb.c
> @@ -1303,8 +1303,7 @@ static void rtl8365mb_get_strings(struct dsa_switch *ds, int port, u32 stringset
>
> for (i = 0; i < RTL8365MB_MIB_END; i++) {
> struct rtl8365mb_mib_counter *mib = &rtl8365mb_mib_counters[i];
> -
> - strncpy(data + i * ETH_GSTRING_LEN, mib->name, ETH_GSTRING_LEN);
> + ethtool_sprintf(&data, "%s", mib->name);
Is there any particular reason why you opted for the "%s" printf format
specifier when you could have simply given mib->name as the single
argument? This comment applies to all the ethtool_sprintf() patches
you've submitted.
On Tue, Oct 10, 2023 at 4:07 AM Vladimir Oltean <[email protected]> wrote:
>
> Hello Justin,
>
> On Mon, Oct 09, 2023 at 10:43:59PM +0000, Justin Stitt wrote:
> > `strncpy` is deprecated for use on NUL-terminated destination strings
> > [1] and as such we should prefer more robust and less ambiguous string
> > interfaces.
> >
> > ethtool_sprintf() is designed specifically for get_strings() usage.
> > Let's replace strncpy in favor of this more robust and easier to
> > understand interface.
> >
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> > Link: https://github.com/KSPP/linux/issues/90
> > Cc: [email protected]
> > Signed-off-by: Justin Stitt <[email protected]>
> > ---
> > Note: build-tested only.
> > ---
> > drivers/net/dsa/realtek/rtl8365mb.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/dsa/realtek/rtl8365mb.c b/drivers/net/dsa/realtek/rtl8365mb.c
> > index 41ea3b5a42b1..d171c18dd354 100644
> > --- a/drivers/net/dsa/realtek/rtl8365mb.c
> > +++ b/drivers/net/dsa/realtek/rtl8365mb.c
> > @@ -1303,8 +1303,7 @@ static void rtl8365mb_get_strings(struct dsa_switch *ds, int port, u32 stringset
> >
> > for (i = 0; i < RTL8365MB_MIB_END; i++) {
> > struct rtl8365mb_mib_counter *mib = &rtl8365mb_mib_counters[i];
> > -
> > - strncpy(data + i * ETH_GSTRING_LEN, mib->name, ETH_GSTRING_LEN);
> > + ethtool_sprintf(&data, "%s", mib->name);
>
> Is there any particular reason why you opted for the "%s" printf format
> specifier when you could have simply given mib->name as the single
> argument? This comment applies to all the ethtool_sprintf() patches
> you've submitted.
Yeah, it causes a -Wformat-security warning for me. I briefly mentioned it
in one of my first patches like this [1].
[1]: https://lore.kernel.org/all/20231005-strncpy-drivers-net-dsa-lan9303-core-c-v2-1-feb452a532db@google.com/
On Tue, Oct 10, 2023 at 10:36 AM Justin Stitt <[email protected]> wrote:
>
> On Tue, Oct 10, 2023 at 4:07 AM Vladimir Oltean <[email protected]> wrote:
> >
> > Hello Justin,
> >
> > On Mon, Oct 09, 2023 at 10:43:59PM +0000, Justin Stitt wrote:
> > > `strncpy` is deprecated for use on NUL-terminated destination strings
> > > [1] and as such we should prefer more robust and less ambiguous string
> > > interfaces.
> > >
> > > ethtool_sprintf() is designed specifically for get_strings() usage.
> > > Let's replace strncpy in favor of this more robust and easier to
> > > understand interface.
> > >
> > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> > > Link: https://github.com/KSPP/linux/issues/90
> > > Cc: [email protected]
> > > Signed-off-by: Justin Stitt <[email protected]>
> > > ---
> > > Note: build-tested only.
> > > ---
> > > drivers/net/dsa/realtek/rtl8365mb.c | 3 +--
> > > 1 file changed, 1 insertion(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/net/dsa/realtek/rtl8365mb.c b/drivers/net/dsa/realtek/rtl8365mb.c
> > > index 41ea3b5a42b1..d171c18dd354 100644
> > > --- a/drivers/net/dsa/realtek/rtl8365mb.c
> > > +++ b/drivers/net/dsa/realtek/rtl8365mb.c
> > > @@ -1303,8 +1303,7 @@ static void rtl8365mb_get_strings(struct dsa_switch *ds, int port, u32 stringset
> > >
> > > for (i = 0; i < RTL8365MB_MIB_END; i++) {
> > > struct rtl8365mb_mib_counter *mib = &rtl8365mb_mib_counters[i];
> > > -
> > > - strncpy(data + i * ETH_GSTRING_LEN, mib->name, ETH_GSTRING_LEN);
> > > + ethtool_sprintf(&data, "%s", mib->name);
> >
> > Is there any particular reason why you opted for the "%s" printf format
> > specifier when you could have simply given mib->name as the single
> > argument? This comment applies to all the ethtool_sprintf() patches
> > you've submitted.
>
> Yeah, it causes a -Wformat-security warning for me. I briefly mentioned it
> in one of my first patches like this [1].
For more context, here's some warnings in the wild:
https://lore.kernel.org/netdev/[email protected]/
>
> [1]: https://lore.kernel.org/all/20231005-strncpy-drivers-net-dsa-lan9303-core-c-v2-1-feb452a532db@google.com/
On Tue, Oct 10, 2023 at 02:48:07PM -0700, Justin Stitt wrote:
> On Tue, Oct 10, 2023 at 10:36 AM Justin Stitt <[email protected]> wrote:
> > > Is there any particular reason why you opted for the "%s" printf format
> > > specifier when you could have simply given mib->name as the single
> > > argument? This comment applies to all the ethtool_sprintf() patches
> > > you've submitted.
> >
> > Yeah, it causes a -Wformat-security warning for me. I briefly mentioned it
> > in one of my first patches like this [1].
>
> For more context, here's some warnings in the wild:
> https://lore.kernel.org/netdev/[email protected]/
>
> >
> > [1]: https://lore.kernel.org/all/20231005-strncpy-drivers-net-dsa-lan9303-core-c-v2-1-feb452a532db@google.com/
Yeah, ok. It's a false positive warning, but I guess it would be too
hard for the compiler to figure that out.
On Mon, Oct 09, 2023 at 10:43:59PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy in favor of this more robust and easier to
> understand interface.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
Reviewed-by: Vladimir Oltean <[email protected]>
On Tue, Oct 10, 2023 at 02:07:17PM +0300, Vladimir Oltean wrote:
> Hello Justin,
>
> On Mon, Oct 09, 2023 at 10:43:59PM +0000, Justin Stitt wrote:
> > `strncpy` is deprecated for use on NUL-terminated destination strings
> > [1] and as such we should prefer more robust and less ambiguous string
> > interfaces.
> >
> > ethtool_sprintf() is designed specifically for get_strings() usage.
> > Let's replace strncpy in favor of this more robust and easier to
> > understand interface.
> >
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> > Link: https://github.com/KSPP/linux/issues/90
> > Cc: [email protected]
> > Signed-off-by: Justin Stitt <[email protected]>
> > ---
> > Note: build-tested only.
> > ---
> > drivers/net/dsa/realtek/rtl8365mb.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/dsa/realtek/rtl8365mb.c b/drivers/net/dsa/realtek/rtl8365mb.c
> > index 41ea3b5a42b1..d171c18dd354 100644
> > --- a/drivers/net/dsa/realtek/rtl8365mb.c
> > +++ b/drivers/net/dsa/realtek/rtl8365mb.c
> > @@ -1303,8 +1303,7 @@ static void rtl8365mb_get_strings(struct dsa_switch *ds, int port, u32 stringset
> >
> > for (i = 0; i < RTL8365MB_MIB_END; i++) {
> > struct rtl8365mb_mib_counter *mib = &rtl8365mb_mib_counters[i];
> > -
> > - strncpy(data + i * ETH_GSTRING_LEN, mib->name, ETH_GSTRING_LEN);
> > + ethtool_sprintf(&data, "%s", mib->name);
>
> Is there any particular reason why you opted for the "%s" printf format
> specifier when you could have simply given mib->name as the single
> argument? This comment applies to all the ethtool_sprintf() patches
> you've submitted.
The primary reason is that without the "%s", any format specifiers in
mib->name will be processed by sprintf(), which could lead to very
unexpected results. One never wants to just pass a string directly to
the sprintf-family of functions for this reason. "%s" is needed to keep
things safe.
-Kees
--
Kees Cook
Hello:
This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <[email protected]>:
On Mon, 09 Oct 2023 22:43:59 +0000 you wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy in favor of this more robust and easier to
> understand interface.
>
> [...]
Here is the summary with links:
- net: dsa: realtek: rtl8365mb: replace deprecated strncpy with ethtool_sprintf
https://git.kernel.org/netdev/net-next/c/e5f061d5e340
You are awesome, thank you!
--
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