diff mbox series

[net,v2,1/2] net: phy: Fix formatting specifier to avoid potential string cuts

Message ID 20250319105813.3102076-2-andriy.shevchenko@linux.intel.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series net: phy: Fix potential string cut when using PHY_ID_FMT | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present fail Series targets non-next tree, but doesn't contain any Fixes tags
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/build_tools success Errors and warnings before: 26 (+0) this patch: 26 (+0)
netdev/cc_maintainers warning 1 maintainers not CCed: andrew@lunn.ch
netdev/build_clang fail Errors and warnings before: 10 this patch: 12
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 362 this patch: 362
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 30 this patch: 30
netdev/source_inline success Was 0 now: 0

Commit Message

Andy Shevchenko March 19, 2025, 10:54 a.m. UTC 
The PHY_ID_FMT is defined with '%02x' which is _minumum_ digits
to be printed. This, in particular, may trigger GCC warning, when
the parameter for the above mentioned specifier is bigger than
a byte. Avoid this, by limiting the amount of digits to be printed
to two. This is okay as the PHY maximum address is 31 and it fits.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/phy.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Andy Shevchenko March 19, 2025, 11:21 a.m. UTC | #1 
On Wed, Mar 19, 2025 at 12:54:33PM +0200, Andy Shevchenko wrote:
> The PHY_ID_FMT is defined with '%02x' which is _minumum_ digits
> to be printed. This, in particular, may trigger GCC warning, when
> the parameter for the above mentioned specifier is bigger than
> a byte. Avoid this, by limiting the amount of digits to be printed
> to two. This is okay as the PHY maximum address is 31 and it fits.

For the curious: additional reading in the commit
46d57a7a8e33 ("docs: printk-formats: Fix hex printing of signed values").
kernel test robot March 19, 2025, 3:37 p.m. UTC | #2 
Hi Andy,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Andy-Shevchenko/net-phy-Fix-formatting-specifier-to-avoid-potential-string-cuts/20250319-190433
base:   net/main
patch link:    https://lore.kernel.org/r/20250319105813.3102076-2-andriy.shevchenko%40linux.intel.com
patch subject: [PATCH net v2 1/2] net: phy: Fix formatting specifier to avoid potential string cuts
config: x86_64-allmodconfig (https://download.01.org/0day-ci/archive/20250319/202503192340.iVN44lM2-lkp@intel.com/config)
compiler: clang version 20.1.0 (https://github.com/llvm/llvm-project 24a30daaa559829ad079f2ff7f73eb4e18095f88)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250319/202503192340.iVN44lM2-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202503192340.iVN44lM2-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/net/usb/ax88172a.c:312:20: warning: format specifies type 'unsigned char' but the argument has type 'u16' (aka 'unsigned short') [-Wformat]
     311 |         snprintf(priv->phy_name, 20, PHY_ID_FMT,
         |                                      ~~~~~~~~~~
     312 |                  priv->mdio->id, priv->phy_addr);
         |                                  ^~~~~~~~~~~~~~
   1 warning generated.


vim +312 drivers/net/usb/ax88172a.c

16626b0cc3d5af Christian Riesch 2012-07-13  260  
16626b0cc3d5af Christian Riesch 2012-07-13  261  static int ax88172a_reset(struct usbnet *dev)
16626b0cc3d5af Christian Riesch 2012-07-13  262  {
16626b0cc3d5af Christian Riesch 2012-07-13  263  	struct asix_data *data = (struct asix_data *)&dev->data;
16626b0cc3d5af Christian Riesch 2012-07-13  264  	struct ax88172a_private *priv = dev->driver_priv;
16626b0cc3d5af Christian Riesch 2012-07-13  265  	int ret;
16626b0cc3d5af Christian Riesch 2012-07-13  266  	u16 rx_ctl;
16626b0cc3d5af Christian Riesch 2012-07-13  267  
16626b0cc3d5af Christian Riesch 2012-07-13  268  	ax88172a_reset_phy(dev, priv->use_embdphy);
16626b0cc3d5af Christian Riesch 2012-07-13  269  
16626b0cc3d5af Christian Riesch 2012-07-13  270  	msleep(150);
d9fe64e511144c Robert Foss      2016-08-29  271  	rx_ctl = asix_read_rx_ctl(dev, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  272  	netdev_dbg(dev->net, "RX_CTL is 0x%04x after software reset\n", rx_ctl);
d9fe64e511144c Robert Foss      2016-08-29  273  	ret = asix_write_rx_ctl(dev, 0x0000, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  274  	if (ret < 0)
16626b0cc3d5af Christian Riesch 2012-07-13  275  		goto out;
16626b0cc3d5af Christian Riesch 2012-07-13  276  
d9fe64e511144c Robert Foss      2016-08-29  277  	rx_ctl = asix_read_rx_ctl(dev, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  278  	netdev_dbg(dev->net, "RX_CTL is 0x%04x setting to 0x0000\n", rx_ctl);
16626b0cc3d5af Christian Riesch 2012-07-13  279  
16626b0cc3d5af Christian Riesch 2012-07-13  280  	msleep(150);
16626b0cc3d5af Christian Riesch 2012-07-13  281  
16626b0cc3d5af Christian Riesch 2012-07-13  282  	ret = asix_write_cmd(dev, AX_CMD_WRITE_IPG0,
16626b0cc3d5af Christian Riesch 2012-07-13  283  			     AX88772_IPG0_DEFAULT | AX88772_IPG1_DEFAULT,
d9fe64e511144c Robert Foss      2016-08-29  284  			     AX88772_IPG2_DEFAULT, 0, NULL, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  285  	if (ret < 0) {
16626b0cc3d5af Christian Riesch 2012-07-13  286  		netdev_err(dev->net, "Write IPG,IPG1,IPG2 failed: %d\n", ret);
16626b0cc3d5af Christian Riesch 2012-07-13  287  		goto out;
16626b0cc3d5af Christian Riesch 2012-07-13  288  	}
16626b0cc3d5af Christian Riesch 2012-07-13  289  
16626b0cc3d5af Christian Riesch 2012-07-13  290  	/* Rewrite MAC address */
16626b0cc3d5af Christian Riesch 2012-07-13  291  	memcpy(data->mac_addr, dev->net->dev_addr, ETH_ALEN);
16626b0cc3d5af Christian Riesch 2012-07-13  292  	ret = asix_write_cmd(dev, AX_CMD_WRITE_NODE_ID, 0, 0, ETH_ALEN,
d9fe64e511144c Robert Foss      2016-08-29  293  			     data->mac_addr, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  294  	if (ret < 0)
16626b0cc3d5af Christian Riesch 2012-07-13  295  		goto out;
16626b0cc3d5af Christian Riesch 2012-07-13  296  
16626b0cc3d5af Christian Riesch 2012-07-13  297  	/* Set RX_CTL to default values with 2k buffer, and enable cactus */
d9fe64e511144c Robert Foss      2016-08-29  298  	ret = asix_write_rx_ctl(dev, AX_DEFAULT_RX_CTL, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  299  	if (ret < 0)
16626b0cc3d5af Christian Riesch 2012-07-13  300  		goto out;
16626b0cc3d5af Christian Riesch 2012-07-13  301  
d9fe64e511144c Robert Foss      2016-08-29  302  	rx_ctl = asix_read_rx_ctl(dev, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  303  	netdev_dbg(dev->net, "RX_CTL is 0x%04x after all initializations\n",
16626b0cc3d5af Christian Riesch 2012-07-13  304  		   rx_ctl);
16626b0cc3d5af Christian Riesch 2012-07-13  305  
d9fe64e511144c Robert Foss      2016-08-29  306  	rx_ctl = asix_read_medium_status(dev, 0);
16626b0cc3d5af Christian Riesch 2012-07-13  307  	netdev_dbg(dev->net, "Medium Status is 0x%04x after all initializations\n",
16626b0cc3d5af Christian Riesch 2012-07-13  308  		   rx_ctl);
16626b0cc3d5af Christian Riesch 2012-07-13  309  
16626b0cc3d5af Christian Riesch 2012-07-13  310  	/* Connect to PHY */
16626b0cc3d5af Christian Riesch 2012-07-13  311  	snprintf(priv->phy_name, 20, PHY_ID_FMT,
16626b0cc3d5af Christian Riesch 2012-07-13 @312  		 priv->mdio->id, priv->phy_addr);
16626b0cc3d5af Christian Riesch 2012-07-13  313  
16626b0cc3d5af Christian Riesch 2012-07-13  314  	priv->phydev = phy_connect(dev->net, priv->phy_name,
16626b0cc3d5af Christian Riesch 2012-07-13  315  				   &ax88172a_adjust_link,
f9a8f83b04e0c3 Florian Fainelli 2013-01-14  316  				   PHY_INTERFACE_MODE_MII);
16626b0cc3d5af Christian Riesch 2012-07-13  317  	if (IS_ERR(priv->phydev)) {
16626b0cc3d5af Christian Riesch 2012-07-13  318  		netdev_err(dev->net, "Could not connect to PHY device %s\n",
16626b0cc3d5af Christian Riesch 2012-07-13  319  			   priv->phy_name);
16626b0cc3d5af Christian Riesch 2012-07-13  320  		ret = PTR_ERR(priv->phydev);
16626b0cc3d5af Christian Riesch 2012-07-13  321  		goto out;
16626b0cc3d5af Christian Riesch 2012-07-13  322  	}
16626b0cc3d5af Christian Riesch 2012-07-13  323  
16626b0cc3d5af Christian Riesch 2012-07-13  324  	netdev_info(dev->net, "Connected to phy %s\n", priv->phy_name);
16626b0cc3d5af Christian Riesch 2012-07-13  325  
16626b0cc3d5af Christian Riesch 2012-07-13  326  	/* During power-up, the AX88172A set the power down (BMCR_PDOWN)
16626b0cc3d5af Christian Riesch 2012-07-13  327  	 * bit of the PHY. Bring the PHY up again.
16626b0cc3d5af Christian Riesch 2012-07-13  328  	 */
16626b0cc3d5af Christian Riesch 2012-07-13  329  	genphy_resume(priv->phydev);
16626b0cc3d5af Christian Riesch 2012-07-13  330  	phy_start(priv->phydev);
16626b0cc3d5af Christian Riesch 2012-07-13  331  
16626b0cc3d5af Christian Riesch 2012-07-13  332  	return 0;
16626b0cc3d5af Christian Riesch 2012-07-13  333  
16626b0cc3d5af Christian Riesch 2012-07-13  334  out:
16626b0cc3d5af Christian Riesch 2012-07-13  335  	return ret;
16626b0cc3d5af Christian Riesch 2012-07-13  336
Russell King (Oracle) March 19, 2025, 3:46 p.m. UTC | #3 
On Wed, Mar 19, 2025 at 12:54:33PM +0200, Andy Shevchenko wrote:
> -#define PHY_ID_FMT "%s:%02x"
> +#define PHY_ID_FMT "%s:%02hhx"

I was going to state whether it is correct to use hh with an "int"
argument, as printf() suggests its only for use with arguments of
type 'signed char' and 'unsigned char'. My suspicion has been
confirmed by the warning the kbuild bot has just reported.

It seems this is not a correct fix for the problem you report.
Andy Shevchenko March 19, 2025, 3:52 p.m. UTC | #4 
On Wed, Mar 19, 2025 at 11:37:19PM +0800, kernel test robot wrote:
> Hi Andy,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on net/main]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Andy-Shevchenko/net-phy-Fix-formatting-specifier-to-avoid-potential-string-cuts/20250319-190433
> base:   net/main
> patch link:    https://lore.kernel.org/r/20250319105813.3102076-2-andriy.shevchenko%40linux.intel.com
> patch subject: [PATCH net v2 1/2] net: phy: Fix formatting specifier to avoid potential string cuts
> config: x86_64-allmodconfig (https://download.01.org/0day-ci/archive/20250319/202503192340.iVN44lM2-lkp@intel.com/config)
> compiler: clang version 20.1.0 (https://github.com/llvm/llvm-project 24a30daaa559829ad079f2ff7f73eb4e18095f88)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250319/202503192340.iVN44lM2-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202503192340.iVN44lM2-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> drivers/net/usb/ax88172a.c:312:20: warning: format specifies type 'unsigned char' but the argument has type 'u16' (aka 'unsigned short') [-Wformat]
>      311 |         snprintf(priv->phy_name, 20, PHY_ID_FMT,
>          |                                      ~~~~~~~~~~
>      312 |                  priv->mdio->id, priv->phy_addr);
>          |                                  ^~~~~~~~~~~~~~
>    1 warning generated.

It's fun: while working around GCC complain, clang does not agree with... :-)
Let's wait more, probably the simplest fix (if this becomes only a single user
of the non-byte parameter) is to move it to u8.
Andy Shevchenko March 19, 2025, 4:16 p.m. UTC | #5 
On Wed, Mar 19, 2025 at 03:46:48PM +0000, Russell King (Oracle) wrote:
> On Wed, Mar 19, 2025 at 12:54:33PM +0200, Andy Shevchenko wrote:

...

> > -#define PHY_ID_FMT "%s:%02x"
> > +#define PHY_ID_FMT "%s:%02hhx"
> 
> I was going to state whether it is correct to use hh with an "int"
> argument, as printf() suggests its only for use with arguments of
> type 'signed char' and 'unsigned char'. My suspicion has been

Yeah...

> It seems this is not a correct fix for the problem you report.

Apparently looks like (from the clang point of view — I compiled it with GCC).

...

Thanks for the review!
kernel test robot March 19, 2025, 5:27 p.m. UTC | #6 
Hi Andy,

kernel test robot noticed the following build errors:

[auto build test ERROR on net/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Andy-Shevchenko/net-phy-Fix-formatting-specifier-to-avoid-potential-string-cuts/20250319-190433
base:   net/main
patch link:    https://lore.kernel.org/r/20250319105813.3102076-2-andriy.shevchenko%40linux.intel.com
patch subject: [PATCH net v2 1/2] net: phy: Fix formatting specifier to avoid potential string cuts
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20250320/202503200024.WkseT3sA-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250320/202503200024.WkseT3sA-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202503200024.WkseT3sA-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   In file included from drivers/net/ethernet/broadcom/genet/bcmmii.c:17:
   drivers/net/ethernet/broadcom/genet/bcmmii.c: In function 'bcmgenet_mii_pd_init':
>> include/linux/phy.h:312:20: warning: '%02hhx' directive output may be truncated writing 2 bytes into a region of size between 0 and 60 [-Wformat-truncation=]
     312 | #define PHY_ID_FMT "%s:%02hhx"
         |                    ^~~~~~~~~~~
   drivers/net/ethernet/broadcom/genet/bcmmii.c:604:53: note: in expansion of macro 'PHY_ID_FMT'
     604 |                 snprintf(phy_name, MII_BUS_ID_SIZE, PHY_ID_FMT,
         |                                                     ^~~~~~~~~~
   include/linux/phy.h:312:24: note: format string is defined here
     312 | #define PHY_ID_FMT "%s:%02hhx"
         |                        ^~~~~~
   include/linux/phy.h:312:20: note: using the range [0, 255] for directive argument
     312 | #define PHY_ID_FMT "%s:%02hhx"
         |                    ^~~~~~~~~~~
   drivers/net/ethernet/broadcom/genet/bcmmii.c:604:53: note: in expansion of macro 'PHY_ID_FMT'
     604 |                 snprintf(phy_name, MII_BUS_ID_SIZE, PHY_ID_FMT,
         |                                                     ^~~~~~~~~~
   drivers/net/ethernet/broadcom/genet/bcmmii.c:604:17: note: 'snprintf' output between 4 and 64 bytes into a destination of size 61
     604 |                 snprintf(phy_name, MII_BUS_ID_SIZE, PHY_ID_FMT,
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     605 |                          mdio_bus_id, pd->phy_address);
         |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
   loongarch64-linux-ld: arch/loongarch/kernel/head.o: relocation R_LARCH_B26 overflow 0xfffffffff3911f74
   arch/loongarch/kernel/head.o: in function `smpboot_entry':
>> (.ref.text+0x15c): relocation truncated to fit: R_LARCH_B26 against symbol `start_secondary' defined in .text section in arch/loongarch/kernel/smp.o
   loongarch64-linux-ld: final link failed: bad value


vim +312 include/linux/phy.h

   310	
   311	/* Used when trying to connect to a specific phy (mii bus id:phy device id) */
 > 312	#define PHY_ID_FMT "%s:%02hhx"
   313
diff mbox series

Patch

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 19f076a71f94..3b18c241f33e 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -309,7 +309,7 @@  static inline long rgmii_clock(int speed)
 #define PHY_MAX_ADDR	32
 
 /* Used when trying to connect to a specific phy (mii bus id:phy device id) */
-#define PHY_ID_FMT "%s:%02x"
+#define PHY_ID_FMT "%s:%02hhx"
 
 #define MII_BUS_ID_SIZE	61