NULL pointer dereferences in hid-mcp2221

* NULL pointer dereferences in hid-mcp2221
@ 2022-10-25  7:39 Sven Zühlsdorf
  2022-10-25  7:46 ` NULL pointer dereferences in hid-mcp2221 -- kernel config Sven Zühlsdorf
                   ` (3 more replies)
  0 siblings, 4 replies; 8+ messages in thread
From: Sven Zühlsdorf @ 2022-10-25  7:39 UTC (permalink / raw)
  To: Rishi Gupta; +Cc: linux-i2c, linux-kernel

[-- Attachment #1: Type: text/plain, Size: 11029 bytes --]

Hi,

I've run into two NULL pointer dereferences when loading the MCP2221 driver.
Initially I observed them running the kernel used by yocto kirkstone
(currently 5.15.68) but can reproduce them with a vanilla 6.1-rc1 as well.
All line numbers below are for hid-mcp2221.c, taken from 6.1-rc1.

The first one was easy to identify, in mcp2221_probe line 874 `hdev->hidraw`
was NULL since I compiled the kernel without CONFIG_HIDRAW enabled. Should
CONFIG_HID_MCP2221 perhaps depend on or imply CONFIG_HIDRAW?

For the second one however, I'm stuck. The dereference happens at the top of
mcp_smbus_xfer since i2c_get_adapdata in line 307 returned NULL. Looking at
the call trace (see [dmesg output] below), mcp_smbus_xfer gets called
indirectly from mcp2221_probe via i2c_add_adapter in line 876, directly
before a call to i2c_set_adapdata. Since I couldn't identify another call to
i2c_set_adapdata or a write to `mcp->adapter.dev.driver_data` that could
potentially have initialized that field, I attempted to swap the order of
calling i2c_set_adapdata and i2c_add_adapter, see [attempted fix] below. While
the driver now loads without issue, no devices appear on the i2c bus:
# i2cdetect -l
i2c-0   smbus           SMBus I801 adapter at 5000              SMBus adapter
i2c-1   i2c             MCP2221 usb-i2c bridge on hidraw0       I2C adapter
# i2cdetect -y 1
      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --


When booting a distribution kernel (Ubunutu 22.04 with kernel 5.15.39) the bus
is populated as expected:
# i2cdetect -l
i2c-0   smbus           SMBus CMI adapter cmi                   SMBus adapter
i2c-1   smbus           SMBus iSMT adapter at 20fffab9000       SMBus adapter
i2c-2   smbus           SMBus I801 adapter at 5000              SMBus adapter
i2c-3   i2c             MCP2221 usb-i2c bridge on hidraw0       I2C adapter
# i2cdetect -y 3
      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- 3b -- -- -- --
40: -- -- -- -- -- -- -- -- UU -- -- -- UU -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: 70 -- -- -- -- -- -- --

In the patches applied by Ubuntu I couldn't find anything that'd explain this
change in behavior. Regarding their kernel configuration the situation is
similar: Even incorporating almost all of Ubuntu's additions (minus some
signing and integrity stuff) into the config I've been using results in the
NULL pointer dereference in mcp_smbus_xfer. Since this still might be a case of
me missing some config options, I'll post my config in a response to this mail.


There seem to be two recent patch series for this driver:
https://lore.kernel.org/all/20221001005208.8010-1-matt.ranostay@konsulko.com/
https://lore.kernel.org/all/20220926202239.16379-1-Enrik.Berkhan@inka.de/
I tested both, but the behavior stays the same.

[attempted fix]

--- a/drivers/hid/hid-mcp2221.c	2022-09-19 09:31:22.539691089 +0200
+++ b/drivers/hid/hid-mcp2221.c	2022-09-20 15:21:37.576196331 +0200
@@ -873,12 +873,22 @@
  			"MCP2221 usb-i2c bridge on hidraw%d",
  			((struct hidraw *)hdev->hidraw)->minor);

+	int adapdata_change = 0;
+	if(!i2c_get_adapdata(&mcp->adapter))
+	{
+		adapdata_change = 1;
+		hid_warn(hdev, "got NULL adapdata\n");
+		i2c_set_adapdata(&mcp->adapter, mcp);
+	}
  	ret = i2c_add_adapter(&mcp->adapter);
  	if (ret) {
+		if(adapdata_change)
+		{
+			i2c_set_adapdata(&mcp->adapter, NULL);
+		}
  		hid_err(hdev, "can't add usb-i2c adapter: %d\n", ret);
  		goto err_i2c;
  	}
-	i2c_set_adapdata(&mcp->adapter, mcp);

  	/* Setup GPIO chip */
  	mcp->gc = devm_kzalloc(&hdev->dev, sizeof(*mcp->gc), GFP_KERNEL);

[dmesg output]
Shortened to just the trace, I'll post the full dmesg output in a response to
this mail.
[    1.898107] usb 1-3.4: new full-speed USB device number 5 using xhci_hcd
[    1.990607] cdc_acm 1-3.4:1.0: ttyACM1: USB ACM device
[    1.991509] hid-generic 0003:04D8:00DD.0003: hiddev96,hidraw2: USB HID v1.11 Device [Microchip Technology Inc. MCP2221 USB-I2C/UART Combo] on usb-0000:00:1e.0-3.4/input2
[    1.998390] mcp2221 0003:04D8:00DD.0003: hidraw2: USB HID v1.11 Device [Microchip Technology Inc. MCP2221 USB-I2C/UART Combo] on usb-0000:00:1e.0-3.4/input2
[    2.050149] i2c_dev: adapter [MCP2221 usb-i2c bridge on hidraw2] registered as minor 1
[    2.050166] i2c i2c-1: adapter [MCP2221 usb-i2c bridge on hidraw2] registered
[    2.050173] i2c i2c-1: found normal entry for adapter 1, addr 0x48
[    2.050179] BUG: kernel NULL pointer dereference, address: 0000000000000000
[    2.057180] #PF: supervisor read access in kernel mode
[    2.062347] #PF: error_code(0x0000) - not-present page
[    2.067517] PGD 0 P4D 0 
[    2.070069] Oops: 0000 [#1] PREEMPT SMP
[    2.073931] CPU: 7 PID: 287 Comm: systemd-udevd Not tainted 6.1.0-rc1-yocto-standard-upstream #1
[    2.082761] Hardware name: Default string Default string/Default string, BIOS 1.01.10.AR01 08/05/2022
[    2.092025] RIP: 0010:mcp_smbus_xfer+0x29/0x348 [hid_mcp2221]
[    2.097811] Code: 00 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 55 45 89 cd 41 54 45 89 c4 53 48 83 ec 08 48 8b 9f e8 00 00 00 89 75 d4 89 4d d0 <48> 8b 3b 48 8b 87 b8 1b 00 00 48 8b 40 20 48 85 c0 74 07 be 20 00
[    2.116673] RSP: 0018:ffffa6c4409ab748 EFLAGS: 00010296
[    2.121929] RAX: ffffffffc0509fc0 RBX: 0000000000000000 RCX: 0000000000000000
[    2.129104] RDX: 0000000000000000 RSI: 0000000000000048 RDI: ffff9957c69b5830
[    2.136278] RBP: ffffa6c4409ab778 R08: 0000000000000000 R09: 0000000000000000
[    2.143450] R10: ffff995b3fede000 R11: ffff995b3ff8e000 R12: 0000000000000000
[    2.150625] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[    2.157797] FS:  00007f5b4ee65600(0000) GS:ffff995b301c0000(0000) knlGS:0000000000000000
[    2.165932] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.171710] CR2: 0000000000000000 CR3: 0000000108c9b002 CR4: 0000000000770ee0
[    2.178884] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    2.186059] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    2.193232] PKRU: 55555554
[    2.195959] Call Trace:
[    2.198423]  <TASK>
[    2.200540]  __i2c_smbus_xfer+0x105/0x3d0
[    2.204578]  ? mcp_i2c_xfer+0x160/0x160 [hid_mcp2221]
[    2.209663]  i2c_smbus_xfer+0x62/0xe0
[    2.213350]  i2c_default_probe+0xf1/0x130
[    2.217384]  i2c_detect.isra.0.cold+0xf4/0x220
[    2.229989]  ? kernfs_add_one+0xe8/0x130
[    2.233941]  ? preempt_count_add+0x7a/0xc0
[    2.238063]  ? _raw_spin_lock_irqsave+0x1e/0x50
[    2.242623]  ? __process_new_driver+0x30/0x30
[    2.247007]  __process_new_adapter+0x18/0x20
[    2.251304]  bus_for_each_drv+0x82/0xd0
[    2.255167]  i2c_register_adapter.cold+0x133/0x1f4
[    2.259990]  i2c_add_adapter+0x5c/0x80
[    2.263764]  mcp2221_probe+0x138/0x250 [hid_mcp2221]
[    2.268762]  ? hid_lookup_quirk+0x7f/0x190
[    2.272884]  hid_device_probe+0xf5/0x160
[    2.285748]  really_probe+0xdf/0x290
[    2.298964]  ? pm_runtime_barrier+0x55/0x90
[    2.311392]  __driver_probe_device+0x78/0xe0
[    2.323310]  driver_probe_device+0x24/0xe0
[    2.327431]  __device_attach_driver+0x7d/0x100
[    2.337243]  ? driver_allows_async_probing+0x60/0x60
[    2.348108]  bus_for_each_drv+0x82/0xd0
[    2.351969]  ? __hid_register_driver+0x90/0x90
[    2.356439]  __device_attach+0xc1/0x1f0
[    2.360302]  ? __hid_register_driver+0x90/0x90
[    2.364773]  device_attach+0x10/0x20
[    2.368372]  device_reprobe+0x4a/0x90
[    2.372059]  __hid_bus_reprobe_drivers+0x56/0x60
[    2.376704]  bus_for_each_dev+0x7c/0xc0
[    2.386344]  ? hid_destroy_device+0x60/0x60
[    2.390554]  __hid_bus_driver_added+0x2c/0x40
[    2.394937]  bus_for_each_drv+0x82/0xd0
[    2.398800]  __hid_register_driver+0x7d/0x90
[    2.403096]  ? 0xffffffffc07c2000
[    2.406434]  mcp2221_driver_init+0x23/0x1000 [hid_mcp2221]
[    2.411955]  do_one_initcall+0x4f/0x210
[    2.415817]  ? kmalloc_trace+0x2a/0xa0
[    2.419593]  do_init_module+0x52/0x200
[    2.423367]  load_module+0x1a78/0x1c50
[    2.427142]  __do_sys_finit_module+0xbb/0x110
[    2.431525]  ? __do_sys_finit_module+0xbb/0x110
[    2.436086]  __x64_sys_finit_module+0x18/0x20
[    2.440469]  do_syscall_64+0x3d/0x90
[    2.444070]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
[    2.449154] RIP: 0033:0x7f5b4efc202d
[    2.452755] Code: c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c3 4d 0e 00 f7 d8 64 89 01 48
[    2.471614] RSP: 002b:00007ffe16a04a18 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[    2.479225] RAX: ffffffffffffffda RBX: 00005651bb4c0670 RCX: 00007f5b4efc202d
[    2.479226] RDX: 0000000000000000 RSI: 00007f5b4f13636b RDI: 0000000000000006
[    2.479227] RBP: 00007ffe16a04a40 R08: 0000000000000000 R09: 0000000000000000
[    2.491744] R10: 0000000000000006 R11: 0000000000000246 R12: 00007f5b4f13636b
[    2.491745] R13: 0000000000000000 R14: 0000000000020000 R15: 00005651bb4c0670
[    2.491748]  </TASK>
[    2.506091] Modules linked in: hid_mcp2221(+) ice(+) igc
[    2.519128]  sch_fq_codel tmp421 configfs
[    2.519132] CR2: 0000000000000000
[    2.528505] ---[ end trace 0000000000000000 ]---
[    2.566155] RIP: 0010:mcp_smbus_xfer+0x29/0x348 [hid_mcp2221]
[    2.587646] Code: 00 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 55 45 89 cd 41 54 45 89 c4 53 48 83 ec 08 48 8b 9f e8 00 00 00 89 75 d4 89 4d d0 <48> 8b 3b 48 8b 87 b8 1b 00 00 48 8b 40 20 48 85 c0 74 07 be 20 00
[    2.587648] RSP: 0018:ffffa6c4409ab748 EFLAGS: 00010296
[    2.598855] RAX: ffffffffc0509fc0 RBX: 0000000000000000 RCX: 0000000000000000
[    2.598856] RDX: 0000000000000000 RSI: 0000000000000048 RDI: ffff9957c69b5830
[    2.608406] RBP: ffffa6c4409ab778 R08: 0000000000000000 R09: 0000000000000000
[    2.608407] R10: ffff995b3fede000 R11: ffff995b3ff8e000 R12: 0000000000000000
[    2.608408] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[    2.618830] FS:  00007f5b4ee65600(0000) GS:ffff995b301c0000(0000) knlGS:0000000000000000
[    2.618832] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.642332] CR2: 0000000000000000 CR3: 0000000108c9b002 CR4: 0000000000770ee0
[    2.642333] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    2.642334] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    2.642335] PKRU: 55555554

-- 
Sven Zühlsdorf
Software Engineer
ViGEM GmbH

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