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 <201903170317.IWsOYXBe%lkp@intel.com>
In-Reply-To: <201903170317.IWsOYXBe%lkp@intel.com>
From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Mon, 18 Mar 2019 17:53:00 +0100
Message-ID: <CAAeHK+wo5pC2W_zRYMYTAXQbh2a_2=ifgJhMDBZ7p1m=chfSbw@mail.gmail.com>
Subject: Re: [PATCH v11 09/14] kernel, arm64: untag user pointers in prctl_set_mm*
To:     kbuild test robot <lkp@intel.com>
Cc:     kbuild-all@01.org, Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
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        Andrew Morton <akpm@linux-foundation.org>,
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        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
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On Sat, Mar 16, 2019 at 8:32 PM kbuild test robot <lkp@intel.com> wrote:
>
> Hi Andrey,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on linus/master]
> [also build test ERROR on v5.0 next-20190306]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
>
> url:    https://github.com/0day-ci/linux/commits/Andrey-Konovalov/uaccess-add-untagged_addr-definition-for-other-arches/20190317-015913
> config: x86_64-randconfig-x012-201911 (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=x86_64
>
> All errors (new ones prefixed by >>):
>
>    kernel/sys.c: In function 'prctl_set_mm_map':
> >> kernel/sys.c:1996:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->start_code = untagged_addr(prctl_map.start_code);
>               ^~
>    kernel/sys.c:1997:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->end_code = untagged_addr(prctl_map.end_code);
>               ^~
>    kernel/sys.c:1998:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->start_data = untagged_addr(prctl_map.start_data);
>               ^~
>    kernel/sys.c:1999:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->end_data = untagged_addr(prctl_map.end_data);
>               ^~
>    kernel/sys.c:2000:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->start_brk = untagged_addr(prctl_map.start_brk);
>               ^~
>    kernel/sys.c:2001:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->brk  = untagged_addr(prctl_map.brk);
>               ^~
>    kernel/sys.c:2002:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->start_stack = untagged_addr(prctl_map.start_stack);
>               ^~
>    kernel/sys.c:2003:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->arg_start = untagged_addr(prctl_map.arg_start);
>               ^~
>    kernel/sys.c:2004:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->arg_end = untagged_addr(prctl_map.arg_end);
>               ^~
>    kernel/sys.c:2005:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->env_start = untagged_addr(prctl_map.env_start);
>               ^~
>    kernel/sys.c:2006:11: error: invalid type argument of '->' (have 'struct prctl_mm_map')
>      prctl_map->env_end = untagged_addr(prctl_map.env_end);
>               ^~
>
> vim +1996 kernel/sys.c

Right, I didn't have the related config options enabled when I did the
testing...

>
>   1974
>   1975  #ifdef CONFIG_CHECKPOINT_RESTORE
>   1976  static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data_size)
>   1977  {
>   1978          struct prctl_mm_map prctl_map = { .exe_fd = (u32)-1, };
>   1979          unsigned long user_auxv[AT_VECTOR_SIZE];
>   1980          struct mm_struct *mm = current->mm;
>   1981          int error;
>   1982
>   1983          BUILD_BUG_ON(sizeof(user_auxv) != sizeof(mm->saved_auxv));
>   1984          BUILD_BUG_ON(sizeof(struct prctl_mm_map) > 256);
>   1985
>   1986          if (opt == PR_SET_MM_MAP_SIZE)
>   1987                  return put_user((unsigned int)sizeof(prctl_map),
>   1988                                  (unsigned int __user *)addr);
>   1989
>   1990          if (data_size != sizeof(prctl_map))
>   1991                  return -EINVAL;
>   1992
>   1993          if (copy_from_user(&prctl_map, addr, sizeof(prctl_map)))
>   1994                  return -EFAULT;
>   1995
> > 1996          prctl_map->start_code   = untagged_addr(prctl_map.start_code);
>   1997          prctl_map->end_code     = untagged_addr(prctl_map.end_code);
>   1998          prctl_map->start_data   = untagged_addr(prctl_map.start_data);
>   1999          prctl_map->end_data     = untagged_addr(prctl_map.end_data);
>   2000          prctl_map->start_brk    = untagged_addr(prctl_map.start_brk);
>   2001          prctl_map->brk          = untagged_addr(prctl_map.brk);
>   2002          prctl_map->start_stack  = untagged_addr(prctl_map.start_stack);
>   2003          prctl_map->arg_start    = untagged_addr(prctl_map.arg_start);
>   2004          prctl_map->arg_end      = untagged_addr(prctl_map.arg_end);
>   2005          prctl_map->env_start    = untagged_addr(prctl_map.env_start);
>   2006          prctl_map->env_end      = untagged_addr(prctl_map.env_end);
>   2007
>   2008          error = validate_prctl_map(&prctl_map);
>   2009          if (error)
>   2010                  return error;
>   2011
>   2012          if (prctl_map.auxv_size) {
>   2013                  memset(user_auxv, 0, sizeof(user_auxv));
>   2014                  if (copy_from_user(user_auxv,
>   2015                                     (const void __user *)prctl_map.auxv,
>   2016                                     prctl_map.auxv_size))
>   2017                          return -EFAULT;
>   2018
>   2019                  /* Last entry must be AT_NULL as specification requires */
>   2020                  user_auxv[AT_VECTOR_SIZE - 2] = AT_NULL;
>   2021                  user_auxv[AT_VECTOR_SIZE - 1] = AT_NULL;
>   2022          }
>   2023
>   2024          if (prctl_map.exe_fd != (u32)-1) {
>   2025                  error = prctl_set_mm_exe_file(mm, prctl_map.exe_fd);
>   2026                  if (error)
>   2027                          return error;
>   2028          }
>   2029
>   2030          /*
>   2031           * arg_lock protects concurent updates but we still need mmap_sem for
>   2032           * read to exclude races with sys_brk.
>   2033           */
>   2034          down_read(&mm->mmap_sem);
>   2035
>   2036          /*
>   2037           * We don't validate if these members are pointing to
>   2038           * real present VMAs because application may have correspond
>   2039           * VMAs already unmapped and kernel uses these members for statistics
>   2040           * output in procfs mostly, except
>   2041           *
>   2042           *  - @start_brk/@brk which are used in do_brk but kernel lookups
>   2043           *    for VMAs when updating these memvers so anything wrong written
>   2044           *    here cause kernel to swear at userspace program but won't lead
>   2045           *    to any problem in kernel itself
>   2046           */
>   2047
>   2048          spin_lock(&mm->arg_lock);
>   2049          mm->start_code  = prctl_map.start_code;
>   2050          mm->end_code    = prctl_map.end_code;
>   2051          mm->start_data  = prctl_map.start_data;
>   2052          mm->end_data    = prctl_map.end_data;
>   2053          mm->start_brk   = prctl_map.start_brk;
>   2054          mm->brk         = prctl_map.brk;
>   2055          mm->start_stack = prctl_map.start_stack;
>   2056          mm->arg_start   = prctl_map.arg_start;
>   2057          mm->arg_end     = prctl_map.arg_end;
>   2058          mm->env_start   = prctl_map.env_start;
>   2059          mm->env_end     = prctl_map.env_end;
>   2060          spin_unlock(&mm->arg_lock);
>   2061
>   2062          /*
>   2063           * Note this update of @saved_auxv is lockless thus
>   2064           * if someone reads this member in procfs while we're
>   2065           * updating -- it may get partly updated results. It's
>   2066           * known and acceptable trade off: we leave it as is to
>   2067           * not introduce additional locks here making the kernel
>   2068           * more complex.
>   2069           */
>   2070          if (prctl_map.auxv_size)
>   2071                  memcpy(mm->saved_auxv, user_auxv, sizeof(user_auxv));
>   2072
>   2073          up_read(&mm->mmap_sem);
>   2074          return 0;
>   2075  }
>   2076  #endif /* CONFIG_CHECKPOINT_RESTORE */
>   2077
>
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
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