tree: https://git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git auth.v2 head: 9107ea4a3526c6801b38b7a2345b7372278a35ba commit: 245c033d4a03bc806ab510cf072583c9076eb9d2 [3/12] lib/base64: RFC4648-compliant base64 encoding config: um-x86_64_defconfig (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git/commi... git remote add hare-scsi-devel https://git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git git fetch --no-tags hare-scsi-devel auth.v2 git checkout 245c033d4a03bc806ab510cf072583c9076eb9d2 # save the attached .config to linux build tree make W=1 ARCH=um SUBARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): 27 | int base64_encode(const u8 *src, int len, char *dst) | ^~~~~~~~~~~~~ 74 | int base64_decode(const char *src, int len, u8 *dst) | ^~~~~~~~~~~~~ vim +/base64_encode +27 lib/base64.c 12 13 static const char lookup_table[65] = 14 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 15 16 /** 17 * base64_encode() - base64-encode some bytes 18 * @src: the bytes to encode 19 * @len: number of bytes to encode 20 * @dst: (output) the base64-encoded string. Not NUL-terminated. 21 * 22 * Encodes the input string using characters from the set [A-Za-z0-9+,]. 23 * The encoded string is roughly 4/3 times the size of the input string. 24 * 25 * Return: length of the encoded string 26 */ 28 { 29 int i, bits = 0; 30 u32 ac = 0; 31 char *cp = dst; 32 33 for (i = 0; i < len; i++) { 34 ac = (ac << 8) | src[i]; 35 bits += 8; 36 if (bits < 24) 37 continue; 38 do { 39 bits -= 6; 40 *cp++ = lookup_table[(ac >> bits) & 0x3f]; 41 } while (bits); 42 ac = 0; 43 } 44 if (bits) { 45 int more = 0; 46 47 if (bits < 16) 48 more = 2; 49 ac = (ac << (2 + more)); 50 bits += (2 + more); 51 do { 52 bits -= 6; 53 *cp++ = lookup_table[(ac >> bits) & 0x3f]; 54 } while (bits); 55 *cp++ = '='; 56 if (more) 57 *cp++ = '='; 58 } 59 60 return cp - dst; 61 } 62 EXPORT_SYMBOL_GPL(base64_encode); 63 64 /** 65 * base64_decode() - base64-decode some bytes 66 * @src: the base64-encoded string to decode 67 * @len: number of bytes to decode 68 * @dst: (output) the decoded bytes. 69 * 70 * Decodes the base64-encoded bytes @src according to RFC 4648. 71 * 72 * Return: number of decoded bytes 73 */ --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org