When lookahead has "consumed" some characters (la_count > 0), n_tty_receive_buf_standard() and n_tty_receive_buf_closing() for characters beyond the la_count are given wrong cp/fp offsets which leads to duplicating and losing some characters.
If la_count > 0, correct buffer pointers and make count consistent too (the latter is not strictly necessary to fix the issue but seems more logical to adjust all variables immediately to keep state consistent).
Reported-by: Vadym Krevs vkrevs@yahoo.com Fixes: 6bb6fa6908eb ("tty: Implement lookahead to process XON/XOFF timely") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218834 Tested-by: Vadym Krevs vkrevs@yahoo.com Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com --- drivers/tty/n_tty.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index f252d0b5a434..5e9ca4376d68 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1619,15 +1619,25 @@ static void __receive_buf(struct tty_struct *tty, const u8 *cp, const u8 *fp, else if (ldata->raw || (L_EXTPROC(tty) && !preops)) n_tty_receive_buf_raw(tty, cp, fp, count); else if (tty->closing && !L_EXTPROC(tty)) { - if (la_count > 0) + if (la_count > 0) { n_tty_receive_buf_closing(tty, cp, fp, la_count, true); - if (count > la_count) - n_tty_receive_buf_closing(tty, cp, fp, count - la_count, false); + cp += la_count; + if (fp) + fp += la_count; + count -= la_count; + } + if (count > 0) + n_tty_receive_buf_closing(tty, cp, fp, count, false); } else { - if (la_count > 0) + if (la_count > 0) { n_tty_receive_buf_standard(tty, cp, fp, la_count, true); - if (count > la_count) - n_tty_receive_buf_standard(tty, cp, fp, count - la_count, false); + cp += la_count; + if (fp) + fp += la_count; + count -= la_count; + } + if (count > 0) + n_tty_receive_buf_standard(tty, cp, fp, count, false);
flush_echoes(tty); if (tty->ops->flush_chars)