gcc -02引起内存溢出'unsigned i'应修订为'volatile unsigned i'

2017-12-13 10:44:19
gcc -02引起内存溢出'unsigned i'应修订为'volatile unsigned i'

1.3.100 driver/char/random.c
static inline void add_entropy_word(struct random_bucket *r,
                    const __u32 input)
{
    volatile unsigned i; //old : unsigned i;
    __u32 w;

w = (input << r->input_rotate) | (input >> (32 - r->input_rotate));
    i = r->add_ptr = (r->add_ptr - 1) & (POOLWORDS-1);
    if (i)
        r->input_rotate = (r->input_rotate + 7) & 31;
    else
        /*
         * At the beginning of the pool, add an extra 7 bits
         * rotation, so that successive passes spread the
         * input bits across the pool evenly.
         */
        r->input_rotate = (r->input_rotate + 14) & 31;

/* XOR in the various taps */
    w ^= r->pool[(i+TAP1)&(POOLWORDS-1)];
    w ^= r->pool[(i+TAP2)&(POOLWORDS-1)];
    w ^= r->pool[(i+TAP3)&(POOLWORDS-1)];
    w ^= r->pool[(i+TAP4)&(POOLWORDS-1)];
    w ^= r->pool[(i+TAP5)&(POOLWORDS-1)];
    w ^= r->pool[i];
    /* Rotate w left 1 bit (stolen from SHA) and store */
    r->pool[i] = (w << 1) | (w >> 31);
}