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authorPan Xinhui <xinhuix.pan@intel.com>2015-03-28 10:42:56 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-06-06 08:19:35 -0700
commitad34c79b5fda56d036ce3274f286a454887d76cc (patch)
tree82fa790f470266a2e0a7c4b7a5709cb8eca8dedf
parent68275f52fca669da9aba3692c08048faa36059f9 (diff)
tty/n_gsm.c: fix a memory leak when gsmtty is removed
commit 8f9cfeed3eae86c70d3b04445a6f2036b27b6304 upstream. when gsmtty_remove put dlci, it will cause memory leak if dlci->port's refcount is zero. So we do the cleanup work in .cleanup callback instead. dlci will be last put in two call chains. 1) gsmld_close -> gsm_cleanup_mux -> gsm_dlci_release -> dlci_put 2) gsmld_remove -> dlci_put so there is a race. the memory leak depends on the race. In call chain 2. we hit the memory leak. below comment tells. release_tty -> tty_driver_remove_tty -> gsmtty_remove -> dlci_put -> tty_port_destructor (WARN_ON(port->itty) and return directly) | tty->port->itty = NULL; | tty_kref_put ---> release_one_tty -> gsmtty_cleanup (added by our patch) So our patch fix the memory leak by doing the cleanup work after tty core did. Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com> Fixes: dfabf7ffa30585 Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/n_gsm.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 2ebe47b78a3e..5bfd8076b21f 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -3166,7 +3166,7 @@ static int gsmtty_break_ctl(struct tty_struct *tty, int state)
return gsmtty_modem_update(dlci, encode);
}
-static void gsmtty_remove(struct tty_driver *driver, struct tty_struct *tty)
+static void gsmtty_cleanup(struct tty_struct *tty)
{
struct gsm_dlci *dlci = tty->driver_data;
struct gsm_mux *gsm = dlci->gsm;
@@ -3174,7 +3174,6 @@ static void gsmtty_remove(struct tty_driver *driver, struct tty_struct *tty)
dlci_put(dlci);
dlci_put(gsm->dlci[0]);
mux_put(gsm);
- driver->ttys[tty->index] = NULL;
}
/* Virtual ttys for the demux */
@@ -3195,7 +3194,7 @@ static const struct tty_operations gsmtty_ops = {
.tiocmget = gsmtty_tiocmget,
.tiocmset = gsmtty_tiocmset,
.break_ctl = gsmtty_break_ctl,
- .remove = gsmtty_remove,
+ .cleanup = gsmtty_cleanup,
};