[PATCH] tty: Prevent hw state corruption in exclusive mode reopen
From: Peter Hurley <hidden>
Date: 2014-12-30 12:34:51
Also in:
lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
Exclusive mode ttys (TTY_EXCLUSIVE) do not allow further reopens; fail the condition before associating the file pointer and calling the driver open() method. Prevents DTR programming when the tty is already in exclusive mode. Reported-by: Shreyas Bethur <redacted> Signed-off-by: Peter Hurley <redacted> --- drivers/tty/tty_io.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 4f35b43..8629087 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c@@ -2091,6 +2091,11 @@ retry_open: goto err_file; } + if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN)) { + retval = -EBUSY; + goto err_file; + } + tty_add_file(tty, filp); check_tty_count(tty, __func__);
@@ -2106,10 +2111,6 @@ retry_open: retval = -ENODEV; filp->f_flags = saved_flags; - if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && - !capable(CAP_SYS_ADMIN)) - retval = -EBUSY; - if (retval) { #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
--
2.2.1