| Message ID | 20231005-strncpy-drivers-net-dsa-lan9303-core-c-v2-1-feb452a532db@google.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2] net: dsa: lan9303: use ethtool_sprintf() for lan9303_get_strings() | expand |
On Thu, Oct 05, 2023 at 06:56:50PM +0000, Justin Stitt wrote: > This pattern of strncpy with some pointer arithmetic setting fixed-sized > intervals with string literal data is a bit weird so let's use > ethtool_sprintf() as this has more obvious behavior and is less-error > prone. > > Nicely, we also get to drop a usage of the now deprecated strncpy() [1]. > > One might consider this pattern: > | ethtool_sprintf(&buf, lan9303_mib[u].name); > ... but this triggers a -Wformat-security warning. > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] > Link: https://github.com/KSPP/linux/issues/90 > Cc: linux-hardening@vger.kernel.org > Cc: Kees Cook <keescook@chromium.org> > Signed-off-by: Justin Stitt <justinstitt@google.com> Ah, cool ethtool_sprintf() works. Maybe some day we can fix the whole API to actually have bounds, but yes, this is fine. Reviewed-by: Kees Cook <keescook@chromium.org>
From: Justin Stitt <justinstitt@google.com> Date: Thu, 05 Oct 2023 18:56:50 +0000 > This pattern of strncpy with some pointer arithmetic setting fixed-sized > intervals with string literal data is a bit weird so let's use > ethtool_sprintf() as this has more obvious behavior and is less-error > prone. [...] > diff --git a/drivers/net/dsa/lan9303-core.c b/drivers/net/dsa/lan9303-core.c > index ee67adeb2cdb..95a8e5168c2a 100644 > --- a/drivers/net/dsa/lan9303-core.c > +++ b/drivers/net/dsa/lan9303-core.c > @@ -1007,14 +1007,14 @@ static const struct lan9303_mib_desc lan9303_mib[] = { > static void lan9303_get_strings(struct dsa_switch *ds, int port, > u32 stringset, uint8_t *data) > { > + u8 *buf = data; Is it needed here? I thought you could pass @data directly to ethtool_sprintf(), if it doesn't mind. > unsigned int u; > > if (stringset != ETH_SS_STATS) > return; > > for (u = 0; u < ARRAY_SIZE(lan9303_mib); u++) { > - strncpy(data + u * ETH_GSTRING_LEN, lan9303_mib[u].name, > - ETH_GSTRING_LEN); > + ethtool_sprintf(&buf, "%s", lan9303_mib[u].name); > } > } Either way, this was a nitpick, so Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com> > > > --- > base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 > change-id: 20231005-strncpy-drivers-net-dsa-lan9303-core-c-6386858e5c22 > > Best regards, > -- > Justin Stitt <justinstitt@google.com> > Thanks, Olek
On Thu, 05 Oct 2023 18:56:50 +0000, Justin Stitt wrote: > This pattern of strncpy with some pointer arithmetic setting fixed-sized > intervals with string literal data is a bit weird so let's use > ethtool_sprintf() as this has more obvious behavior and is less-error > prone. > > Nicely, we also get to drop a usage of the now deprecated strncpy() [1]. > > [...] Applied to for-next/hardening, thanks! [1/1] net: dsa: lan9303: use ethtool_sprintf() for lan9303_get_strings() https://git.kernel.org/kees/c/f1c7720549bf Take care,
On Thu, 30 Nov 2023 13:59:58 -0800 Kees Cook wrote: > Applied to for-next/hardening, thanks! > > [1/1] net: dsa: lan9303: use ethtool_sprintf() for lan9303_get_strings() > https://git.kernel.org/kees/c/f1c7720549bf Please drop this, it got changes requested on our end because I figured Alexander's comment is worth addressing.
On Thu, Nov 30, 2023 at 10:40:21PM -0800, Jakub Kicinski wrote: > On Thu, 30 Nov 2023 13:59:58 -0800 Kees Cook wrote: > > Applied to for-next/hardening, thanks! > > > > [1/1] net: dsa: lan9303: use ethtool_sprintf() for lan9303_get_strings() > > https://git.kernel.org/kees/c/f1c7720549bf > > Please drop this, it got changes requested on our end because > I figured Alexander's comment is worth addressing. Done. Justin, can you please refresh this patch (or, actually, make sure the ethtool_puts() series lands?)
On Fri, Dec 1, 2023 at 10:19 AM Kees Cook <keescook@chromium.org> wrote: > > On Thu, Nov 30, 2023 at 10:40:21PM -0800, Jakub Kicinski wrote: > > On Thu, 30 Nov 2023 13:59:58 -0800 Kees Cook wrote: > > > Applied to for-next/hardening, thanks! > > > > > > [1/1] net: dsa: lan9303: use ethtool_sprintf() for lan9303_get_strings() > > > https://git.kernel.org/kees/c/f1c7720549bf > > > > Please drop this, it got changes requested on our end because > > I figured Alexander's comment is worth addressing. > > Done. Justin, can you please refresh this patch (or, actually, make sure > the ethtool_puts() series lands?) Yeah, let's let this patch die. The ethtool_puts() is on v5 and is getting good reviewed-by's. I suspect it will be in soon. Then I'll double back and do right by the intent of this patch. > > -- > Kees Cook Justin
diff --git a/drivers/net/dsa/lan9303-core.c b/drivers/net/dsa/lan9303-core.c index ee67adeb2cdb..95a8e5168c2a 100644 --- a/drivers/net/dsa/lan9303-core.c +++ b/drivers/net/dsa/lan9303-core.c @@ -1007,14 +1007,14 @@ static const struct lan9303_mib_desc lan9303_mib[] = { static void lan9303_get_strings(struct dsa_switch *ds, int port, u32 stringset, uint8_t *data) { + u8 *buf = data; unsigned int u; if (stringset != ETH_SS_STATS) return; for (u = 0; u < ARRAY_SIZE(lan9303_mib); u++) { - strncpy(data + u * ETH_GSTRING_LEN, lan9303_mib[u].name, - ETH_GSTRING_LEN); + ethtool_sprintf(&buf, "%s", lan9303_mib[u].name); } }
This pattern of strncpy with some pointer arithmetic setting fixed-sized intervals with string literal data is a bit weird so let's use ethtool_sprintf() as this has more obvious behavior and is less-error prone. Nicely, we also get to drop a usage of the now deprecated strncpy() [1]. One might consider this pattern: | ethtool_sprintf(&buf, lan9303_mib[u].name); ... but this triggers a -Wformat-security warning. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Justin Stitt <justinstitt@google.com> Suggested-by: Alexander Lobakin <aleksander.lobakin@intel.com> --- Changes in v2: - use ethtool_sprintf (thanks Alexander) - Link to v1: https://lore.kernel.org/r/20231005-strncpy-drivers-net-dsa-lan9303-core-c-v1-1-5a66c538147e@google.com --- Note: build-tested only. --- drivers/net/dsa/lan9303-core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 change-id: 20231005-strncpy-drivers-net-dsa-lan9303-core-c-6386858e5c22 Best regards, -- Justin Stitt <justinstitt@google.com>