[PATCH] Fix refcount leak in tty_port.c

[Gianluca Anzolin <gianluca@sottospazio.it>]

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Hello,

In linux 3.10 in the file drivers/tty/tty_port.c the function
tty_port_tty_hangup may leak a tty reference:

        struct tty_struct *tty = tty_port_tty_get(port);

        if (tty && (!check_clocal || !C_CLOCAL(tty))) {
                tty_hangup(tty);
                tty_kref_put(tty);
        }

If tty != NULL and the second condition is false we never call tty_kref_put and
the reference is leaked.

Fix by nesting two if statements.

Signed-off-by: Gianluca Anzolin <gianluca@sottospazio.it>

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diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 121aeb9..2198f7d 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -256,8 +256,9 @@ void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
 {
 	struct tty_struct *tty = tty_port_tty_get(port);
 
-	if (tty && (!check_clocal || !C_CLOCAL(tty))) {
-		tty_hangup(tty);
+	if (tty) {
+		if (!check_clocal || !C_CLOCAL(tty))
+			tty_hangup(tty);
 		tty_kref_put(tty);
 	}
 }