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Re: [PATCH] Don't all __access_noerrno with stack protector from __tunables_init [BZ #21744]
On Tue, Jul 18, 2017 at 6:52 AM, Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
> On 18/07/2017 10:44, H.J. Lu wrote:
>> This should work for Linux.
>>
>> Thanks.
>>
>
> Now with a proper patch:
>
> [PATCH] tunables: Use direct syscall for access (BZ#21744)
>
> The function maybe_enable_malloc_check, which is called by
> __tunables_init, calls __access_noerrno. It isn't problem when
> symbol is is in ld.so, which has a special version of __access_noerrno
> without stack protector. But when glibc is built with stack protector,
> maybe_enable_malloc_check in libc.a can't call the regular version of
> __access_noerrno with stack protector.
>
> This patch changes how Linux defines the __access_noerrno to be an
> inline call instead and thus preventing defining different build
> rules for ld/static and shared.
>
> H.J. Lu <hongjiu.lu@intel.com>
> Adhemerval Zanella <adhemerval.zanella@linaro.org>
Missing [BZ#21744]
> * elf/dl-tunables.c: Include not-errno.h header.
> * include/unistd.h (__access_noerrno): Remove definition.
> * sysdeps/unix/sysv/linux/access.c (__access_noerrno): Likewise.
> * sysdeps/generic/not-errno.h: New file.
> * sysdeps/unix/sysv/linux/not-errno.h: Likewise.
> ---
> ChangeLog | 9 +++++++++
> elf/dl-tunables.c | 2 ++
> include/unistd.h | 7 -------
> sysdeps/generic/not-errno.h | 19 +++++++++++++++++++
> sysdeps/unix/sysv/linux/access.c | 15 ---------------
> sysdeps/unix/sysv/linux/not-errno.h | 30 ++++++++++++++++++++++++++++++
> 6 files changed, 60 insertions(+), 22 deletions(-)
> create mode 100644 sysdeps/generic/not-errno.h
> create mode 100644 sysdeps/unix/sysv/linux/not-errno.h
>
> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
> index 44c160c..231fb8c 100644
> --- a/elf/dl-tunables.c
> +++ b/elf/dl-tunables.c
> @@ -29,6 +29,8 @@
> #define TUNABLES_INTERNAL 1
> #include "dl-tunables.h"
>
> +#include <not-errno.h>
> +
> #if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
> # define GLIBC_TUNABLES "GLIBC_TUNABLES"
> #endif
> diff --git a/include/unistd.h b/include/unistd.h
> index 5b2a414..7f1c2cc 100644
> --- a/include/unistd.h
> +++ b/include/unistd.h
> @@ -182,12 +182,5 @@ extern int __getlogin_r_loginuid (char *name, size_t namesize)
> # include <dl-unistd.h>
> # endif
>
> -# if IS_IN (rtld) || !defined SHARED
> -/* __access variant that does not set errno. Used in very early initialization
> - code in libc.a and ld.so. It follows access return semantics (zero for
> - sucess otherwise a value different than 0). */
> -extern __typeof (__access) __access_noerrno attribute_hidden;
> -# endif
> -
> # endif
> #endif
> diff --git a/sysdeps/generic/not-errno.h b/sysdeps/generic/not-errno.h
> new file mode 100644
> index 0000000..2aac095
> --- /dev/null
> +++ b/sysdeps/generic/not-errno.h
> @@ -0,0 +1,19 @@
> +/* Syscall wrapper that do not set errno. Generic version.
> + Copyright (C) 2017 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +extern __typeof (__access) __access_noerrno attribute_hidden;
> diff --git a/sysdeps/unix/sysv/linux/access.c b/sysdeps/unix/sysv/linux/access.c
> index 67e69bd..366b6b6 100644
> --- a/sysdeps/unix/sysv/linux/access.c
> +++ b/sysdeps/unix/sysv/linux/access.c
> @@ -21,21 +21,6 @@
> #include <sysdep-cancel.h>
>
> int
> -__access_noerrno (const char *file, int type)
> -{
> - int res;
> - INTERNAL_SYSCALL_DECL (err);
> -#ifdef __NR_access
> - res = INTERNAL_SYSCALL_CALL (access, err, file, type);
> -#else
> - res = INTERNAL_SYSCALL_CALL (faccessat, err, AT_FDCWD, file, type);
> -#endif
> - if (INTERNAL_SYSCALL_ERROR_P (res, err))
> - return INTERNAL_SYSCALL_ERRNO (res, err);
> - return 0;
> -}
> -
> -int
> __access (const char *file, int type)
> {
> #ifdef __NR_access
> diff --git a/sysdeps/unix/sysv/linux/not-errno.h b/sysdeps/unix/sysv/linux/not-errno.h
> new file mode 100644
> index 0000000..4957038
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/not-errno.h
> @@ -0,0 +1,30 @@
> +/* Syscall wrapper that do not set errno. Linux version.
> + Copyright (C) 2017 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +/* This function is used on maybe_enable_malloc_check (elf/dl-tunables.c)
> + and to avoid having to build/use multiple versions if stack protection
> + in enabled it is defined as inline. */
> +static inline int
> +__access_noerrno (const char *pathname, int mode)
> +{
> +#ifdef __NR_access
> + return INTERNAL_SYSCALL_CALL (access, pathname, mode);
> +#else
> + return INTERNAL_SYSCALL_CALL (faccessat, AT_FDCWD, file, type);
> +#endif
> +}
These are wrong. INTERNAL_SYSCALL_CALL needs a dummy err.
This seems to work:
diff --git a/sysdeps/unix/sysv/linux/not-errno.h
b/sysdeps/unix/sysv/linux/not-errno.h
index 4957038160..a03c399f95 100644
--- a/sysdeps/unix/sysv/linux/not-errno.h
+++ b/sysdeps/unix/sysv/linux/not-errno.h
@@ -23,8 +23,8 @@ static inline int
__access_noerrno (const char *pathname, int mode)
{
#ifdef __NR_access
- return INTERNAL_SYSCALL_CALL (access, pathname, mode);
+ return INTERNAL_SYSCALL_CALL (access, err, pathname, mode);
#else
- return INTERNAL_SYSCALL_CALL (faccessat, AT_FDCWD, file, type);
+ return INTERNAL_SYSCALL_CALL (faccessat, err, AT_FDCWD, file, type);
#endif
}
--
H.J.