[PATCH 5.14 150/172] ipack: ipoctal: fix tty-registration error handling

Greg Kroah-Hartman
2021-10-04T13:40:03Z

From: Johan Hovold <johan@kernel.org>

commit cd20d59291d1790dc74248476e928f57fc455189 upstream.

Registration of the ipoctal tty devices is unlikely to fail, but if it
ever does, make sure not to deregister a never registered tty device
(and dereference a NULL pointer) when the driver is later unbound.

Fixes: 2afb41d9d30d ("Staging: ipack/devices/ipoctal: Check tty_register_device return value.")
Cc: stable@vger.kernel.org # 3.7
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210917114622.5412-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/ipack/devices/ipoctal.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/drivers/ipack/devices/ipoctal.c
+++ b/drivers/ipack/devices/ipoctal.c
@@ -33,6 +33,7 @@ struct ipoctal_channel {
unsigned int pointer_read;
unsigned int pointer_write;
struct tty_port tty_port;
+ bool tty_registered;
union scc2698_channel __iomem *regs;
union scc2698_block __iomem *block_regs;
unsigned int board_id;
@@ -397,9 +398,11 @@ static int ipoctal_inst_slot(struct ipoc
i, NULL, channel, NULL);
if (IS_ERR(tty_dev)) {
dev_err(&ipoctal->dev->dev, "Failed to register tty device.\n");
+ tty_port_free_xmit_buf(&channel->tty_port);
tty_port_destroy(&channel->tty_port);
continue;
}
+ channel->tty_registered = true;
}

/*
@@ -699,6 +702,10 @@ static void __ipoctal_remove(struct ipoc

for (i = 0; i < NR_CHANNELS; i++) {
struct ipoctal_channel *channel = &ipoctal->channel[i];
+
+ if (!channel->tty_registered)
+ continue;
+
tty_unregister_device(ipoctal->tty_drv, i);
tty_port_free_xmit_buf(&channel->tty_port);
tty_port_destroy(&channel->tty_port);