diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2015-06-27 09:21:32 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-08-10 12:21:57 -0700 |
| commit | ba3961ad681981dc74fcd519b8f98be8bc3ac381 (patch) | |
| tree | a2a94cb95dec4e7df68a555d0cd2e4c5a13959e3 | |
| parent | f3ef6ad3e4501dae41b0015a3bd8e179b56bdfd8 (diff) | |
n_tty: signal and flush atomically
commit 3b19e032295647b7be2aa3be62510db4aaeda759 upstream.
When handling signalling char, claim the termios write lock before
signalling waiting readers and writers to prevent further i/o
before flushing the echo and output buffers. This prevents a
userspace signal handler which may output from racing the terminal
flush.
Reference: Bugzilla #99351 ("Output truncated in ssh session after...")
Fixes: commit d2b6f44779d3 ("n_tty: Fix signal handling flushes")
Reported-by: Filipe Brandenburger <filbranden@google.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/n_tty.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 396344cb011f..16ed0b6c7f9c 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1108,19 +1108,29 @@ static void eraser(unsigned char c, struct tty_struct *tty) * Locking: ctrl_lock */ -static void isig(int sig, struct tty_struct *tty) +static void __isig(int sig, struct tty_struct *tty) { - struct n_tty_data *ldata = tty->disc_data; struct pid *tty_pgrp = tty_get_pgrp(tty); if (tty_pgrp) { kill_pgrp(tty_pgrp, sig, 1); put_pid(tty_pgrp); } +} - if (!L_NOFLSH(tty)) { +static void isig(int sig, struct tty_struct *tty) +{ + struct n_tty_data *ldata = tty->disc_data; + + if (L_NOFLSH(tty)) { + /* signal only */ + __isig(sig, tty); + + } else { /* signal and flush */ up_read(&tty->termios_rwsem); down_write(&tty->termios_rwsem); + __isig(sig, tty); + /* clear echo buffer */ mutex_lock(&ldata->output_lock); ldata->echo_head = ldata->echo_tail = 0; |