[ 02/49] sunsu: Fix panic in case of nonexistent port at "console=ttySY" cmdline option

Greg Kroah-Hartman
2013-03-26T23:01:55Z

From: Tkhai Kirill <tkhai@yandex.ru>

[ Upstream commit cb29529ea0030e60ef1bbbf8399a43d397a51526 ]

If a machine has X (X < 4) sunsu ports and cmdline
option "console=ttySY" is passed, where X < Y <= 4,
than the following panic happens:

Unable to handle kernel NULL pointer dereference
TPC: <sunsu_console_setup+0x78/0xe0>
RPC: <sunsu_console_setup+0x74/0xe0>
I7: <register_console+0x378/0x3e0>
Call Trace:
[0000000000453a38] register_console+0x378/0x3e0
[0000000000576fa0] uart_add_one_port+0x2e0/0x340
[000000000057af40] su_probe+0x160/0x2e0
[00000000005b8a4c] platform_drv_probe+0xc/0x20
[00000000005b6c2c] driver_probe_device+0x12c/0x220
[00000000005b6da8] __driver_attach+0x88/0xa0
[00000000005b4df4] bus_for_each_dev+0x54/0xa0
[00000000005b5a54] bus_add_driver+0x154/0x260
[00000000005b7190] driver_register+0x50/0x180
[00000000006d250c] sunsu_init+0x18c/0x1e0
[00000000006c2668] do_one_initcall+0xe8/0x160
[00000000006c282c] kernel_init_freeable+0x12c/0x1e0
[0000000000603764] kernel_init+0x4/0x100
[0000000000405f64] ret_from_syscall+0x1c/0x2c
[0000000000000000] (null)

1)Fix the panic;
2)Increment registered port number every successful
probe.

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/sunsu.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)

--- a/drivers/tty/serial/sunsu.c
+++ b/drivers/tty/serial/sunsu.c
@@ -968,6 +968,7 @@ static struct uart_ops sunsu_pops = {
#define UART_NR 4

static struct uart_sunsu_port sunsu_ports[UART_NR];
+static int nr_inst; /* Number of already registered ports */

#ifdef CONFIG_SERIO

@@ -1337,13 +1338,8 @@ static int __init sunsu_console_setup(st
printk("Console: ttyS%d (SU)\n",
(sunsu_reg.minor - 64) + co->index);

- /*
- * Check whether an invalid uart number has been specified, and
- * if so, search for the first available port that does have
- * console support.
- */
- if (co->index >= UART_NR)
- co->index = 0;
+ if (co->index > nr_inst)
+ return -ENODEV;
port = &sunsu_ports[co->index].port;

/*
@@ -1408,7 +1404,6 @@ static enum su_type __devinit su_get_typ

static int __devinit su_probe(struct platform_device *op)
{
- static int inst;
struct device_node *dp = op->dev.of_node;
struct uart_sunsu_port *up;
struct resource *rp;
@@ -1418,16 +1413,16 @@ static int __devinit su_probe(struct pla

type = su_get_type(dp);
if (type == SU_PORT_PORT) {
- if (inst >= UART_NR)
+ if (nr_inst >= UART_NR)
return -EINVAL;
- up = &sunsu_ports[inst];
+ up = &sunsu_ports[nr_inst];
} else {
up = kzalloc(sizeof(*up), GFP_KERNEL);
if (!up)
return -ENOMEM;
}

- up->port.line = inst;
+ up->port.line = nr_inst;

spin_lock_init(&up->port.lock);

@@ -1461,6 +1456,8 @@ static int __devinit su_probe(struct pla
}
dev_set_drvdata(&op->dev, up);

+ nr_inst++;
+
return 0;
}

@@ -1488,7 +1485,7 @@ static int __devinit su_probe(struct pla

dev_set_drvdata(&op->dev, up);

- inst++;
+ nr_inst++;

return 0;