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| author | Pan Xinhui <xinhuix.pan@intel.com> | 2015-03-28 10:42:56 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-05-10 19:25:32 +0200 |
| commit | 8f9cfeed3eae86c70d3b04445a6f2036b27b6304 (patch) | |
| tree | 2582a9a80a8961dc8f0598570c77bc871f05598e /drivers/tty/n_gsm.c | |
| parent | ec61847855094d6f6144340b26f14203f25dd4e9 (diff) | |
| download | lwn-8f9cfeed3eae86c70d3b04445a6f2036b27b6304.tar.gz lwn-8f9cfeed3eae86c70d3b04445a6f2036b27b6304.zip | |
tty/n_gsm.c: fix a memory leak when gsmtty is removed
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)
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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
Cc: stable <stable@vger.kernel.org> # 3.14+
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_gsm.c')
| -rw-r--r-- | drivers/tty/n_gsm.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 91abc00aa833..2c34c3249972 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -3170,7 +3170,7 @@ 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; @@ -3178,7 +3178,6 @@ 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 */ @@ -3199,7 +3198,7 @@ static const struct tty_operations gsmtty_ops = { .tiocmget = gsmtty_tiocmget, .tiocmset = gsmtty_tiocmset, .break_ctl = gsmtty_break_ctl, - .remove = gsmtty_remove, + .cleanup = gsmtty_cleanup, }; |