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    Subject[PATCH 5/5] tty: fix tty_line must not be equal to number of allocated tty pointers in tty driver
    Date
    From: Nathael Pajani <nathael.pajani@ed3l.fr>

    I found a bug "by chance" in drivers/char/tty_io.c

    I mean "by chance" because I was just reading the code of the
    tty_find_polling_driver() to make a new tty_find_by_name() function.

    In tty_find_polling_driver() the driver actually test "tty_line <=
    p->num" while num refers to the number of struct tty_struct pointers
    allocated for the p->ttys (p is a tty_driver), and tty_line is scanned
    in a tty name, which can be for example ttyS2. Then tty_line equals 2.
    And if p->num is 2, we have only p->ttys[0] and p->ttys[1], but no
    p->ttys[2].

    This is actually unharmful, for tty_find_polling_driver() is used only
    in drivers/serial/kgdboc.c, and there's a test over there to find a
    console with a matching index, which will never happen.

    This is still a bug anyway.

    Signed-off-by: Nathael Pajani <nathael.pajani@ed3l.fr>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    ---
    drivers/char/tty_io.c | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
    index 949067a..613c852 100644
    --- a/drivers/char/tty_io.c
    +++ b/drivers/char/tty_io.c
    @@ -355,7 +355,7 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
    if (*stp == '\0')
    stp = NULL;

    - if (tty_line >= 0 && tty_line <= p->num && p->ops &&
    + if (tty_line >= 0 && tty_line < p->num && p->ops &&
    p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
    res = tty_driver_kref_get(p);
    *line = tty_line;
    --
    1.7.2


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