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    SubjectRe: potential-null-pointer-dereference-in-amiga-serial-driver.patch added to -mm tree
    Date
    On Tuesday 31 May 2005 13:08, akpm@osdl.org wrote:
    > A pointer is dereferenced before it is null-checked.

    > --- 25/drivers/char/amiserial.c~potential-null-pointer-dereference-in-amiga-serial-driver
    > +++ 25-akpm/drivers/char/amiserial.c

    > static void rs_put_char(struct tty_struct *tty, unsigned char ch)
    > {
    > - struct async_struct *info = (struct async_struct *)tty->driver_data;
    > + struct async_struct *info;
    > unsigned long flags;
    >
    > + if (!tty)
    > + return;

    Can ->put_char be ever called with tty being NULL? From my reading of
    drivers/char/n_tty.c it can't.

    Every single time ->put_char is used a-la

    tty->driver->put_char(tty, '\r');

    So, tty will be dereferenced before function call. Same for static inline
    put_char() there.

    > +
    > + info = tty->driver_data;

    > static int rs_write(struct tty_struct * tty, const unsigned char *buf, int count)
    > {

    > - struct async_struct *info = (struct async_struct *)tty->driver_data;
    > + struct async_struct *info;
    > unsigned long flags;
    >
    > + if (!tty)
    > + return 0;

    Same question.

    > +
    > + info = tty->driver_data;
    -
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