08 Mar, 2011

1 commit

  • The current tty_audit_add_data code:

    do {
    size_t run;

    run = N_TTY_BUF_SIZE - buf->valid;
    if (run > size)
    run = size;
    memcpy(buf->data + buf->valid, data, run);
    buf->valid += run;
    data += run;
    size -= run;
    if (buf->valid == N_TTY_BUF_SIZE)
    tty_audit_buf_push_current(buf);
    } while (size != 0);

    If the current buffer is full, kernel will then call tty_audit_buf_push_current
    to empty the buffer. But if we disabled audit at the same time, tty_audit_buf_push()
    returns immediately if audit_enabled is zero. Without emptying the buffer.
    With obvious effect on tty_audit_add_data() that ends up spinning in that loop,
    copying 0 bytes at each iteration and attempting to push each time without any effect.
    Holding the lock all along.

    Suggested-by: Alexander Viro
    Signed-off-by: Xiaotian Feng
    Signed-off-by: Greg Kroah-Hartman

    Xiaotian Feng
     

05 Nov, 2010

1 commit