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authorAlan Cox <alan@lxorguk.ukuu.org.uk>2008-08-26 19:55:58 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2008-08-27 14:37:09 -0700
commita152db71d962f405f7e9be5c818bddf6d1be50a7 (patch)
treeec9bd5c50f1e925318488d585a8504a552a63f30
parentf753f3272b4d2108d1e4b121ddcde504737a8693 (diff)
tty: Fix termios tty window resize race with pty/tty pair
Kanru Chen posted a patch versus the old code which deals with the case where you resize the pty side of a pty/tty pair. In that situation the termios data is updated for both pty and tty but the locks are not held for the right side. This implements the fix differently against the updated tty code. Patch by self but the hard bit (noticing and fixing the bug) is thanks to Kanru Chen. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/char/tty_io.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index a27160ba21d7..daeb8f766971 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2498,7 +2498,7 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
/**
* tty_do_resize - resize event
* @tty: tty being resized
- * @real_tty: real tty (if using a pty/tty pair)
+ * @real_tty: real tty (not the same as tty if using a pty/tty pair)
* @rows: rows (character)
* @cols: cols (character)
*
@@ -2512,7 +2512,8 @@ int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
struct pid *pgrp, *rpgrp;
unsigned long flags;
- mutex_lock(&tty->termios_mutex);
+ /* For a PTY we need to lock the tty side */
+ mutex_lock(&real_tty->termios_mutex);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
/* Get the PID values and reference them so we can
@@ -2533,7 +2534,7 @@ int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
tty->winsize = *ws;
real_tty->winsize = *ws;
done:
- mutex_unlock(&tty->termios_mutex);
+ mutex_unlock(&real_tty->termios_mutex);
return 0;
}

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