memcheck/tests/pdb-realloc.c

   1 // This test-case exposes a bug that was present in the compressed V bit
   2 // handling for a while.  The problem was that when
   3 // copy_address_range_state() copied a VA_BITS2_OTHER value, it failed to
   4 // also copy the corresponding entry in the sec-V-bits table.  Then later on
   5 // when we searched for the sec-V-bits entry for the copied-to location, it
   6 // failed to find it:
   7 //
   8 //   Memcheck: mc_main.c:766 (get_sec_vbits8): Assertion 'n' failed.
   9 //   Memcheck: get_sec_vbits8: no node for address 0x4017440 (0x4017441)
  10
  11 #include <stdlib.h>
  12
  13 int main(void)
  14 {
  15    int i, t = 0;
  16    char* x = malloc(1000);
  17
  18    // Write some PDBs (partially defined bytes)
  19    for (i = 0; i < 1000; i++)
  20       x[i] &= (i & 0xff);
  21
  22    // realloc them, invoking copy_address_range_state()
  23    x = realloc(x, 10000);
  24
  25    // Read the PDBs -- this caused a sec-V-bits lookup failure.
  26    for (i = 0; i < 1000; i++)
  27       t += x[i];
  28
  29    __asm__ __volatile__ ("" :: "r"(t));
  30
  31    return 0;
  32 }
  33