1  /* BZ #18877, BZ #21270, and BZ #24699 mmap offset test.
       2  
       3     Copyright (C) 2015-2023 Free Software Foundation, Inc.
       4     This file is part of the GNU C Library.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library is distributed in the hope that it will be useful,
      12     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #include <stdint.h>
      21  #include <stdio.h>
      22  #include <stdlib.h>
      23  #include <string.h>
      24  #include <unistd.h>
      25  #include <errno.h>
      26  #include <sys/mman.h>
      27  #include <mmap_info.h>
      28  
      29  #include <support/check.h>
      30  
      31  static int fd;
      32  static long int page_shift;
      33  static char fname[] = "/tmp/tst-mmap-offset-XXXXXX";
      34  
      35  static void
      36  do_prepare (int argc, char **argv)
      37  {
      38    fd = mkstemp64 (fname);
      39    if (fd < 0)
      40      FAIL_EXIT1 ("mkstemp failed");
      41  
      42    if (unlink (fname))
      43      FAIL_EXIT1 ("unlink failed");
      44  
      45    long sz = sysconf(_SC_PAGESIZE);
      46    if (sz == -1)
      47      sz = 4096L;
      48    page_shift = ffs (sz) - 1;
      49  }
      50  
      51  #define PREPARE do_prepare
      52  
      53  
      54  /* Check if negative offsets are handled correctly by mmap.  */
      55  static int
      56  do_test_bz18877 (void)
      57  {
      58    const int prot = PROT_READ | PROT_WRITE;
      59    const int flags = MAP_SHARED;
      60    const unsigned long length = 0x10000;
      61    const unsigned long offset = 0xace00000;
      62    const unsigned long size = offset + length;
      63    void *addr;
      64  
      65    if (ftruncate64 (fd, size))
      66      FAIL_RET ("ftruncate64 failed");
      67  
      68    addr = mmap (NULL, length, prot, flags, fd, offset);
      69    if (MAP_FAILED == addr)
      70      FAIL_RET ("mmap failed");
      71  
      72    /* This memcpy is likely to SIGBUS if mmap has messed up with offset.  */
      73    memcpy (addr, fname, sizeof (fname));
      74  
      75    return 0;
      76  }
      77  
      78  /* Check if invalid offset are handled correctly by mmap.  */
      79  static int
      80  do_test_large_offset (void)
      81  {
      82    /* For architectures with sizeof (off_t) < sizeof (off64_t) mmap is
      83       implemented with __SYS_mmap2 syscall and the offset is represented in
      84       multiples of page size.  For offset larger than
      85       '1 << (page_shift + 8 * sizeof (off_t))' (that is, 1<<44 on system with
      86       page size of 4096 bytes) the system call silently truncates the offset.
      87       For this case glibc mmap implementation returns EINVAL.  */
      88    const int prot = PROT_READ | PROT_WRITE;
      89    const int flags = MAP_SHARED;
      90    const int64_t offset = 1ULL << (page_shift + 8 * sizeof (uint32_t));
      91    const size_t length = 4096;
      92  
      93    void *addr = mmap64 (NULL, length, prot, flags, fd, offset);
      94    if (mmap64_maximum_offset (page_shift) < UINT64_MAX)
      95      {
      96        if ((addr != MAP_FAILED) && (errno != EINVAL))
      97  	FAIL_RET ("mmap succeed");
      98      }
      99    else
     100      {
     101        if (addr == MAP_FAILED)
     102  	FAIL_RET ("mmap failed");
     103      }
     104  
     105    return 0;
     106  }
     107  
     108  int
     109  do_test (void)
     110  {
     111    int ret = 0;
     112  
     113    ret += do_test_bz18877 ();
     114    ret += do_test_large_offset ();
     115  
     116    return ret;
     117  }
     118  
     119  #include <support/test-driver.c>