From d175feca89a1c162f60f4e3560ca7bc9437c65eb Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Tue, 22 Mar 2016 18:09:51 +0100 Subject: [PATCH] TTY: n_gsm, fix false positive WARN_ON Dmitry reported, that the current cleanup code in n_gsm can trigger a warning: WARNING: CPU: 2 PID: 24238 at drivers/tty/n_gsm.c:2048 gsm_cleanup_mux+0x166/0x6b0() ... Call Trace: ... [] warn_slowpath_null+0x29/0x30 kernel/panic.c:490 [] gsm_cleanup_mux+0x166/0x6b0 drivers/tty/n_gsm.c:2048 [] gsmld_open+0x5b7/0x7a0 drivers/tty/n_gsm.c:2386 [] tty_ldisc_open.isra.2+0x78/0xd0 drivers/tty/tty_ldisc.c:447 [] tty_set_ldisc+0x1ca/0xa70 drivers/tty/tty_ldisc.c:567 [< inline >] tiocsetd drivers/tty/tty_io.c:2650 [] tty_ioctl+0xb2a/0x2140 drivers/tty/tty_io.c:2883 ... But this is a legal path when open fails to find a space in the gsm_mux array and tries to clean up. So make it a standard test instead of a warning. Reported-by: "Dmitry Vyukov" Cc: Alan Cox Link: http://lkml.kernel.org/r/CACT4Y+bHQbAB68VFi7Romcs-Z9ZW3kQRvcq+BvHH1oa5NcAdLA@mail.gmail.com Fixes: 5a640967 ("tty/n_gsm.c: fix a memory leak in gsmld_open()") Cc: stable Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index c01620780f5b..365dfd8bc42b 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -2045,7 +2045,9 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm) } } spin_unlock(&gsm_mux_lock); - WARN_ON(i == MAX_MUX); + /* open failed before registering => nothing to do */ + if (i == MAX_MUX) + return; /* In theory disconnecting DLCI 0 is sufficient but for some modems this is apparently not the case. */ -- 2.20.1