tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 642b151f45dd54809ea00ecd3976a56c1ec9b53d commit: 0ebeea8ca8a4d1d453ad299aef0507dab04f6e8d bpf: Restrict bpf_probe_read{, str}() only to archs where they work date: 4 days ago config: s390-randconfig-r021-20200519 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 135b877874fae96b4372c8a3fbfaa8ff44ff86e3) reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install s390 cross compiling tool for clang build # apt-get install binutils-s390-linux-gnu git checkout 0ebeea8ca8a4d1d453ad299aef0507dab04f6e8d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:11: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:492:45: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu(__raw_readl(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32' ___constant_swab32(x) : ^ include/uapi/linux/swab.h:20:12: note: expanded from macro '___constant_swab32' (((__u32)(x) & (__u32)0x0000ff00UL) << 8) | ^ In file included from kernel/trace/bpf_trace.c:10: In file included from include/linux/filter.h:13: In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:11: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:492:45: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu(__raw_readl(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32' ___constant_swab32(x) : ^ include/uapi/linux/swab.h:21:12: note: expanded from macro '___constant_swab32' (((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | ^ In file included from kernel/trace/bpf_trace.c:10: In file included from include/linux/filter.h:13: In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:11: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:492:45: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu(__raw_readl(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32' ___constant_swab32(x) : ^ include/uapi/linux/swab.h:22:12: note: expanded from macro '___constant_swab32' (((__u32)(x) & (__u32)0xff000000UL) >> 24))) ^ In file included from kernel/trace/bpf_trace.c:10: In file included from include/linux/filter.h:13: In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:11: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:492:45: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu(__raw_readl(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:120:12: note: expanded from macro '__swab32' __fswab32(x)) ^ In file included from kernel/trace/bpf_trace.c:10: In file included from include/linux/filter.h:13: In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:11: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:503:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writeb(value, PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:513:46: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writew(cpu_to_le16(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:523:46: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writel(cpu_to_le32(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:585:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:593:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:601:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:610:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:619:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:628:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ static const struct bpf_func_proto bpf_probe_read_compat_proto = { ^ static const struct bpf_func_proto bpf_probe_read_compat_str_proto = { ^ 22 warnings generated. vim +/bpf_probe_read_compat_proto +216 kernel/trace/bpf_trace.c 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 215 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 @216 static const struct bpf_func_proto bpf_probe_read_compat_proto = { 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 217 .func = bpf_probe_read_compat, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 218 .gpl_only = true, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 219 .ret_type = RET_INTEGER, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 220 .arg1_type = ARG_PTR_TO_UNINIT_MEM, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 221 .arg2_type = ARG_CONST_SIZE_OR_ZERO, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 222 .arg3_type = ARG_ANYTHING, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 223 }; 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 224 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 225 static __always_inline int 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 226 bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 227 const bool compat) 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 228 { 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 229 int ret = security_locked_down(LOCKDOWN_BPF_READ); 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 230 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 231 if (unlikely(ret < 0)) 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 232 goto out; 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 233 /* 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 234 * The strncpy_from_unsafe_*() call will likely not fill the entire 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 235 * buffer, but that's okay in this circumstance as we're probing 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 236 * arbitrary memory anyway similar to bpf_probe_read_*() and might 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 237 * as well probe the stack. Thus, memory is explicitly cleared 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 238 * only in error case, so that improper users ignoring return 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 239 * code altogether don't copy garbage; otherwise length of string 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 240 * is returned that can be used for bpf_perf_event_output() et al. 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 241 */ 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 242 ret = compat ? strncpy_from_unsafe(dst, unsafe_ptr, size) : 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 243 strncpy_from_unsafe_strict(dst, unsafe_ptr, size); 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 244 if (unlikely(ret < 0)) 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 245 out: 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 246 memset(dst, 0, size); 074f528eed408b4 Daniel Borkmann 2016-04-13 247 return ret; 2541517c32be253 Alexei Starovoitov 2015-03-25 248 } 2541517c32be253 Alexei Starovoitov 2015-03-25 249 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 250 BPF_CALL_3(bpf_probe_read_kernel_str, void *, dst, u32, size, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 251 const void *, unsafe_ptr) 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 252 { 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 253 return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr, false); 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 254 } 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 255 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 256 static const struct bpf_func_proto bpf_probe_read_kernel_str_proto = { 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 257 .func = bpf_probe_read_kernel_str, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 258 .gpl_only = true, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 259 .ret_type = RET_INTEGER, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 260 .arg1_type = ARG_PTR_TO_UNINIT_MEM, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 261 .arg2_type = ARG_CONST_SIZE_OR_ZERO, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 262 .arg3_type = ARG_ANYTHING, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 263 }; 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 264 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 265 BPF_CALL_3(bpf_probe_read_compat_str, void *, dst, u32, size, 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 266 const void *, unsafe_ptr) 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 267 { 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 268 return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr, true); 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 269 } 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 270 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 @271 static const struct bpf_func_proto bpf_probe_read_compat_str_proto = { 6ae08ae3dea2cfa Daniel Borkmann 2019-11-02 272 .func = bpf_probe_read_compat_str, 2541517c32be253 Alexei Starovoitov 2015-03-25 273 .gpl_only = true, 2541517c32be253 Alexei Starovoitov 2015-03-25 274 .ret_type = RET_INTEGER, 39f19ebbf57b403 Alexei Starovoitov 2017-01-09 275 .arg1_type = ARG_PTR_TO_UNINIT_MEM, 9c019e2bc4b2bd8 Yonghong Song 2017-11-12 276 .arg2_type = ARG_CONST_SIZE_OR_ZERO, 2541517c32be253 Alexei Starovoitov 2015-03-25 277 .arg3_type = ARG_ANYTHING, 2541517c32be253 Alexei Starovoitov 2015-03-25 278 }; 2541517c32be253 Alexei Starovoitov 2015-03-25 279 :::::: The code at line 216 was first introduced by commit :::::: 6ae08ae3dea2cfa03dd3665a3c8475c2d429ef47 bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers :::::: TO: Daniel Borkmann <daniel(a)iogearbox.net&gt; :::::: CC: Alexei Starovoitov <ast(a)kernel.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org