[kbuild-all] kernel/trace/bpf_trace.c:216:36: warning: unused variable 'bpf_probe_read_compat_proto'

Tuesday, 19 May 2020

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);
~~~~~~~~~~ ^
...
> kernel/trace/bpf_trace.c:216:36: warning: unused variable
'bpf_probe_read_compat_proto' [-Wunused-const-variable] static const struct
bpf_func_proto bpf_probe_read_compat_proto = {
^
...
> kernel/trace/bpf_trace.c:271:36: warning: unused variable
'bpf_probe_read_compat_str_proto' [-Wunused-const-variable] 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;

---
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[kbuild-all] kernel/trace/bpf_trace.c:216:36: warning: unused variable 'bpf_probe_read_compat_proto'