Le 02/03/2026 à 14:27, [email protected] a écrit :
From: David Laight <[email protected]>
-Wshadow is enabled by W=2 builds and __scoped_user_access() quite
deliberately creates a 'const' shadow of the 'user' address that
references a 'guard page' when the application passes a kernel pointer.
Signed-off-by: David Laight <[email protected]>
There is a problem with this patch:
DESCEND objtool
INSTALL libsubcmd_headers
CALL scripts/checksyscalls.sh
CC kernel/futex/core.o
In file included from ./include/asm-generic/div64.h:27,
from ./arch/powerpc/include/generated/asm/div64.h:1,
from ./include/linux/math.h:6,
from ./include/linux/math64.h:6,
from ./include/linux/time.h:6,
from ./include/linux/compat.h:10,
from kernel/futex/core.c:34:
kernel/futex/futex.h: In function 'futex_get_value_locked':
./include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr'
[-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:9: warning: this 'for' clause does not
guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
./include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
In file included from ././include/linux/compiler_types.h:173,
from <command-line>:
./include/linux/compiler-gcc.h:118:33: note: ...this statement, but the
latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC
diagnostic s))
| ^~~~~~~
./include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
./include/linux/uaccess.h:742:31: note: in expansion of macro
'__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow",
"uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
In file included from ./include/asm-generic/div64.h:27,
from ./arch/powerpc/include/generated/asm/div64.h:1,
from ./include/linux/math.h:6,
from ./include/linux/math64.h:6,
from ./include/linux/time.h:6,
from ./include/linux/compat.h:10,
from kernel/futex/core.c:34:
./include/linux/uaccess.h:743:90: error: '_tmpptr' undeclared (first use
in this function)
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
|
^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
./include/linux/uaccess.h:743:90: note: each undeclared identifier is
reported only once for each function it appears in
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
|
^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:28: error: '_with_done' undeclared (first
use in this function)
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~
./include/linux/uaccess.h:743:17: note: in expansion of macro 'and_with'
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
kernel/futex/core.c: In function 'get_futex_key':
./include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr'
[-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:9: warning: this 'for' clause does not
guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
./include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from ././include/linux/compiler_types.h:173,
from <command-line>:
./include/linux/compiler-gcc.h:118:33: note: ...this statement, but the
latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC
diagnostic s))
| ^~~~~~~
./include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
./include/linux/uaccess.h:742:31: note: in expansion of macro
'__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow",
"uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from ./include/asm-generic/div64.h:27,
from ./arch/powerpc/include/generated/asm/div64.h:1,
from ./include/linux/math.h:6,
from ./include/linux/math64.h:6,
from ./include/linux/time.h:6,
from ./include/linux/compat.h:10,
from kernel/futex/core.c:34:
./include/linux/uaccess.h:743:90: error: '_tmpptr' undeclared (first use
in this function)
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
|
^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:28: error: '_with_done' undeclared (first
use in this function)
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~
./include/linux/uaccess.h:743:17: note: in expansion of macro 'and_with'
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr'
[-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:778:9: note: in expansion of macro
'__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:790:9: note: in expansion of macro
'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:856:9: note: in expansion of macro
'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:9: warning: this 'for' clause does not
guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
./include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:778:9: note: in expansion of macro
'__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:790:9: note: in expansion of macro
'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:856:9: note: in expansion of macro
'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from ././include/linux/compiler_types.h:173,
from <command-line>:
./include/linux/compiler-gcc.h:118:33: note: ...this statement, but the
latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC
diagnostic s))
| ^~~~~~~
./include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
./include/linux/uaccess.h:742:31: note: in expansion of macro
'__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow",
"uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:778:9: note: in expansion of macro
'__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:790:9: note: in expansion of macro
'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:856:9: note: in expansion of macro
'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
make[4]: *** [scripts/Makefile.build:289: kernel/futex/core.o] Error 1
make[3]: *** [scripts/Makefile.build:546: kernel/futex] Error 2
make[2]: *** [scripts/Makefile.build:546: kernel] Error 2
make[1]: *** [/home/chleroy/linux-powerpc/Makefile:2101: .] Error 2
make: *** [Makefile:248: __sub-make] Error 2
---
include/linux/uaccess.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 64bc2492eb99..445391ec5a6d 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -739,7 +739,9 @@ static __always_inline void
__scoped_user_rw_access_end(const void *p)
#define __scoped_user_access(mode, uptr, size, elbl)
\
with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size,
elbl)) \
/* Force modified pointer usage within the scope */
\
- and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr)
+ __diag_push() __diag_ignore_all("-Wshadow", "uptr is readonly
copy") \
+ and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
+ __diag_pop()
/**
* scoped_user_read_access_size - Start a scoped user read access with given
size
