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Subject[PATCH v2 5/5] input: misc: bma150: Register input device after setting private data
Date
From: Jonathan Bakker <xc-racer2@live.ca>

Otherwise we introduce a race condition where userspace can request input
before we're ready leading to null pointer dereference such as

input: bma150 as /devices/platform/i2c-gpio-2/i2c-5/5-0038/input/input3
Unable to handle kernel NULL pointer dereference at virtual address 00000018
pgd = (ptrval)
[00000018] *pgd=55dac831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT ARM
Modules linked in: bma150 input_polldev [last unloaded: bma150]
CPU: 0 PID: 2870 Comm: accelerometer Not tainted 5.0.0-rc3-dirty #46
Hardware name: Samsung S5PC110/S5PV210-based board
PC is at input_event+0x8/0x60
LR is at bma150_report_xyz+0x9c/0xe0 [bma150]
pc : [<80450f70>] lr : [<7f0a614c>] psr: 800d0013
sp : a4c1fd78 ip : 00000081 fp : 00020000
r10: 00000000 r9 : a5e2944c r8 : a7455000
r7 : 00000016 r6 : 00000101 r5 : a7617940 r4 : 80909048
r3 : fffffff2 r2 : 00000000 r1 : 00000003 r0 : 00000000
Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: 54e34019 DAC: 00000051
Process accelerometer (pid: 2870, stack limit = 0x(ptrval))
Stackck: (0xa4c1fd78 to 0xa4c20000)
fd60: fffffff3 fc813f6c
fd80: 40410581 d7530ce3 a5e2817c a7617f00 a5e29404 a5e2817c 00000000 7f008324
fda0: a5e28000 8044f59c a5fdd9d0 a5e2945c a46a4a00 a5e29668 a7455000 80454f10
fdc0: 80909048 a5e29668 a5fdd9d0 a46a4a00 806316d0 00000000 a46a4a00 801df5f0
fde0: 00000000 d7530ce3 a4c1fec0 a46a4a00 00000000 a5fdd9d0 a46a4a08 801df53c
fe00: 00000000 801d74bc a4c1fec0 00000000 a4c1ff70 00000000 a7038da8 00000000
fe20: a46a4a00 801e91fc a411bbe0 801f2e88 00000004 00000000 80909048 00000041
fe40: 00000000 00020000 00000000 dead4ead a6a88da0 00000000 ffffe000 806fcae8
fe60: a4c1fec8 00000000 80909048 00000002 a5fdd9d0 a7660110 a411bab0 00000001
fe80: dead4ead ffffffff ffffffff a4c1fe8c a4c1fe8c d7530ce3 20000013 80909048
fea0: 80909048 a4c1ff70 00000001 fffff000 a4c1e000 00000005 00026038 801eabd8
fec0: a7660110 a411bab0 b9394901 00000006 a696201b 76fb3000 00000000 a7039720
fee0: a5fdd9d0 00000101 00000002 00000096 00000000 00000000 00000000 a4c1ff00
ff00: a6b310f4 805cb174 a6b310f4 00000010 00000fe0 00000010 a4c1e000 d7530ce3
ff20: 00000003 a5f41400 a5f41424 00000000 a6962000 00000000 00000003 00000002
ff40: ffffff9c 000a0000 80909048 d7530ce3 a6962000 00000003 80909048 ffffff9c
ff60: a6962000 801d890c 00000000 00000000 00020000 a7590000 00000004 00000100
ff80: 00000001 d7530ce3 000288b8 00026320 000288b8 00000005 80101204 a4c1e000
ffa0: 00000005 80101000 000288b8 00026320 000288b8 000a0000 00000000 00000000
ffc0: 000288b8 00026320 000288b8 00000005 7eef3bac 000264e8 00028ad8 00026038
ffe0: 00000005 7eef3300 76f76e91 76f78546 800d0030 000288b8 00000000 00000000
[<80450f70>] (input_event) from [<a5e2817c>] (0xa5e2817c)
Code: e1a08148 eaffffa8 e351001f 812fff1e (e590c018)
---[ end trace 1c691ee85f2ff243 ]---

Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
---
drivers/input/misc/bma150.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/input/misc/bma150.c b/drivers/input/misc/bma150.c
index 1cdc8ce97968..64caf43e5bca 100644
--- a/drivers/input/misc/bma150.c
+++ b/drivers/input/misc/bma150.c
@@ -470,7 +470,6 @@ static void bma150_init_input_device(struct bma150_data *bma150,
static int bma150_register_input_device(struct bma150_data *bma150)
{
struct input_dev *idev;
- int error;

idev = devm_input_allocate_device(&bma150->client->dev);
if (!idev)
@@ -482,18 +481,14 @@ static int bma150_register_input_device(struct bma150_data *bma150)
idev->close = bma150_irq_close;
input_set_drvdata(idev, bma150);

- error = input_register_device(idev);
- if (error)
- return error;
-
bma150->input = idev;
- return 0;
+
+ return input_register_device(idev);
}

static int bma150_register_polled_device(struct bma150_data *bma150)
{
struct input_polled_dev *ipoll_dev;
- int error;

ipoll_dev = devm_input_allocate_polled_device(&bma150->client->dev);
if (!ipoll_dev)
@@ -509,14 +504,10 @@ static int bma150_register_polled_device(struct bma150_data *bma150)

bma150_init_input_device(bma150, ipoll_dev->input);

- error = input_register_polled_device(ipoll_dev);
- if (error)
- return error;
-
bma150->input_polled = ipoll_dev;
bma150->input = ipoll_dev->input;

- return 0;
+ return input_register_polled_device(ipoll_dev);
}

int bma150_cfg_from_of(struct device_node *np)
--
2.17.1
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