Re: [PATCH v2 2/2] vsprintf: Move space out of string literals in fourcc_string()

[kernel test robot <lkp@intel.com>]

[-- Attachment #1: Type: text/plain, Size: 5908 bytes --]

Hi Andy,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linux/master]
[also build test WARNING on linus/master v5.17-rc1 next-20220124]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Andy-Shevchenko/vsprintf-Fix-potential-unaligned-access/20220124-224420
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2c271fe77d52a0555161926c232cd5bc07178b39
config: arm-randconfig-r022-20220124 (https://download.01.org/0day-ci/archive/20220125/202201250258.qVWkKB2I-lkp(a)intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/f1895edcabdc5dae0528ffff9c3cb665a937223d
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Andy-Shevchenko/vsprintf-Fix-potential-unaligned-access/20220124-224420
        git checkout f1895edcabdc5dae0528ffff9c3cb665a937223d
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   lib/vsprintf.c: In function 'va_format':
   lib/vsprintf.c:1695:9: warning: function 'va_format' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    1695 |         buf += vsnprintf(buf, end > buf ? end - buf : 0, va_fmt->fmt, va);
         |         ^~~
   lib/vsprintf.c: In function 'fourcc_string':
   lib/vsprintf.c:1794:13: error: implicit declaration of function 'stpcpy' [-Werror=implicit-function-declaration]
    1794 |         p = stpcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
         |             ^~~~~~
>> lib/vsprintf.c:1794:13: warning: incompatible implicit declaration of built-in function 'stpcpy' [-Wbuiltin-declaration-mismatch]
   cc1: some warnings being treated as errors


vim +/stpcpy +1794 lib/vsprintf.c

  1685	
  1686	static char *va_format(char *buf, char *end, struct va_format *va_fmt,
  1687			       struct printf_spec spec, const char *fmt)
  1688	{
  1689		va_list va;
  1690	
  1691		if (check_pointer(&buf, end, va_fmt, spec))
  1692			return buf;
  1693	
  1694		va_copy(va, *va_fmt->va);
> 1695		buf += vsnprintf(buf, end > buf ? end - buf : 0, va_fmt->fmt, va);
  1696		va_end(va);
  1697	
  1698		return buf;
  1699	}
  1700	
  1701	static noinline_for_stack
  1702	char *uuid_string(char *buf, char *end, const u8 *addr,
  1703			  struct printf_spec spec, const char *fmt)
  1704	{
  1705		char uuid[UUID_STRING_LEN + 1];
  1706		char *p = uuid;
  1707		int i;
  1708		const u8 *index = uuid_index;
  1709		bool uc = false;
  1710	
  1711		if (check_pointer(&buf, end, addr, spec))
  1712			return buf;
  1713	
  1714		switch (*(++fmt)) {
  1715		case 'L':
  1716			uc = true;
  1717			fallthrough;
  1718		case 'l':
  1719			index = guid_index;
  1720			break;
  1721		case 'B':
  1722			uc = true;
  1723			break;
  1724		}
  1725	
  1726		for (i = 0; i < 16; i++) {
  1727			if (uc)
  1728				p = hex_byte_pack_upper(p, addr[index[i]]);
  1729			else
  1730				p = hex_byte_pack(p, addr[index[i]]);
  1731			switch (i) {
  1732			case 3:
  1733			case 5:
  1734			case 7:
  1735			case 9:
  1736				*p++ = '-';
  1737				break;
  1738			}
  1739		}
  1740	
  1741		*p = 0;
  1742	
  1743		return string_nocheck(buf, end, uuid, spec);
  1744	}
  1745	
  1746	static noinline_for_stack
  1747	char *netdev_bits(char *buf, char *end, const void *addr,
  1748			  struct printf_spec spec,  const char *fmt)
  1749	{
  1750		unsigned long long num;
  1751		int size;
  1752	
  1753		if (check_pointer(&buf, end, addr, spec))
  1754			return buf;
  1755	
  1756		switch (fmt[1]) {
  1757		case 'F':
  1758			num = *(const netdev_features_t *)addr;
  1759			size = sizeof(netdev_features_t);
  1760			break;
  1761		default:
  1762			return error_string(buf, end, "(%pN?)", spec);
  1763		}
  1764	
  1765		return special_hex_number(buf, end, num, size);
  1766	}
  1767	
  1768	static noinline_for_stack
  1769	char *fourcc_string(char *buf, char *end, const u32 *fourcc,
  1770			    struct printf_spec spec, const char *fmt)
  1771	{
  1772		char output[sizeof("0123 little-endian (0x01234567)")];
  1773		char *p = output;
  1774		unsigned int i;
  1775		u32 orig, val;
  1776	
  1777		if (fmt[1] != 'c' || fmt[2] != 'c')
  1778			return error_string(buf, end, "(%p4?)", spec);
  1779	
  1780		if (check_pointer(&buf, end, fourcc, spec))
  1781			return buf;
  1782	
  1783		orig = get_unaligned(fourcc);
  1784		val = orig & ~BIT(31);
  1785	
  1786		for (i = 0; i < sizeof(u32); i++) {
  1787			unsigned char c = val >> (i * 8);
  1788	
  1789			/* Print non-control ASCII characters as-is, dot otherwise */
  1790			*p++ = isascii(c) && isprint(c) ? c : '.';
  1791		}
  1792	
  1793		*p++ = ' ';
> 1794		p = stpcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
  1795	
  1796		*p++ = ' ';
  1797		*p++ = '(';
  1798		p = special_hex_number(p, output + sizeof(output) - 2, orig, sizeof(u32));
  1799		*p++ = ')';
  1800		*p = '\0';
  1801	
  1802		return string(buf, end, output, spec);
  1803	}
  1804	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org