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Message-ID: <caa425d9-e3a2-3764-6191-b308d94ac549@infradead.org>
Date:   Wed, 2 Nov 2022 17:31:14 -0700
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Subject: Re: NULL pointer dereferences in hid-mcp2221
Content-Language: en-US
To:     =?UTF-8?Q?Sven_Z=c3=bchlsdorf?= <sven.zuehlsdorf@vigem.de>,
        Rishi Gupta <gupt21@gmail.com>
Cc:     linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
References: <79152feb-bcbc-9e3e-e776-13170ae4ef40@vigem.de>
From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <79152feb-bcbc-9e3e-e776-13170ae4ef40@vigem.de>
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Hi--

[adding linux-input mailing list]

On 10/25/22 00:39, Sven Zühlsdorf wrote:
> 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?

Looks to me like it should. Hopefully the HID people can chime in here.

I can't help with the second issue. Rishi?

> 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
> 

-- 
~Randy