Re: [PATCH] dvb_usb_af9005: fix kernel panic on init if the driver is compiled in without IR symbols

[Luca Olivetti <luca@ventoso.org>]

El 29/09/14 20:17, Frank Schäfer ha escrit:
> This patches fixes an ancient bug in the dvb_usb_af9005 driver, which
> has been reported at least in the following threads:
> https://lkml.org/lkml/2009/2/4/350
> https://lkml.org/lkml/2014/9/18/558
> 
> If the driver is compiled in without any IR support (neither
> DVB_USB_AF9005_REMOTE nor custom symbols), the symbol_request calls in
> af9005_usb_module_init() return pointers != NULL although the IR
> symbols are not available.
> 
> This leads to the following oops:
> ...
> [    8.529751] usbcore: registered new interface driver dvb_usb_af9005
> [    8.531584] BUG: unable to handle kernel paging request at 02e00000
> [    8.533385] IP: [<7d9d67c6>] af9005_usb_module_init+0x6b/0x9d
> [    8.535613] *pde = 00000000
> [    8.536416] Oops: 0000 [#1] PREEMPT PREEMPT DEBUG_PAGEALLOCDEBUG_PAGEALLOC
> [    8.537863] CPU: 0 PID: 1 Comm: swapper Not tainted 3.15.0-rc6-00151-ga5c075c #1
> [    8.539827] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
> [    8.541519] task: 89c9a670 ti: 89c9c000 task.ti: 89c9c000
> [    8.541519] EIP: 0060:[<7d9d67c6>] EFLAGS: 00010206 CPU: 0
> [    8.541519] EIP is at af9005_usb_module_init+0x6b/0x9d
> [    8.541519] EAX: 02e00000 EBX: 00000000 ECX: 00000006 EDX: 00000000
> [    8.541519] ESI: 00000000 EDI: 7da33ec8 EBP: 89c9df30 ESP: 89c9df2c
> [    8.541519]  DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068
> [    8.541519] CR0: 8005003b CR2: 02e00000 CR3: 05a54000 CR4: 00000690
> [    8.541519] Stack:
> [    8.541519]  7d9d675b 89c9df90 7d992a49 7d7d5914 89c9df4c 7be3a800 7d08c58c 8a4c3968
> [    8.541519]  89c9df80 7be3a966 00000192 00000006 00000006 7d7d3ff4 8a4c397a 00000200
> [    8.541519]  7d6b1280 8a4c3979 00000006 000009a6 7da32db8 b13eec81 00000006 000009a6
> [    8.541519] Call Trace:
> [    8.541519]  [<7d9d675b>] ? ttusb2_driver_init+0x16/0x16
> [    8.541519]  [<7d992a49>] do_one_initcall+0x77/0x106
> [    8.541519]  [<7be3a800>] ? parameqn+0x2/0x35
> [    8.541519]  [<7be3a966>] ? parse_args+0x113/0x25c
> [    8.541519]  [<7d992bc2>] kernel_init_freeable+0xea/0x167
> [    8.541519]  [<7cf01070>] kernel_init+0x8/0xb8
> [    8.541519]  [<7cf27ec0>] ret_from_kernel_thread+0x20/0x30
> [    8.541519]  [<7cf01068>] ? rest_init+0x10c/0x10c
> [    8.541519] Code: 08 c2 c7 05 44 ed f9 7d 00 00 e0 02 c7 05 40 ed f9 7d 00 00 e0 02 c7 05 3c ed f9 7d 00 00 e0 02 75 1f b8 00 00 e0 02 85 c0 74 16 <a1> 00 00 e0 02 c7 05 54 84 8e 7d 00 00 e0 02 a3 58 84 8e 7d eb
> [    8.541519] EIP: [<7d9d67c6>] af9005_usb_module_init+0x6b/0x9d SS:ESP 0068:89c9df2c
> [    8.541519] CR2: 0000000002e00000
> [    8.541519] ---[ end trace 768b6faf51370fc7 ]---
> 
> The prefered fix would be to convert the whole IR code to use the kernel IR
> infrastructure (which wasn't available at the time this driver had been created).
> 
> Until anyone who still has this old hardware steps up an does the conversion,
> fix it by not calling the symbol_request calls if the driver is compiled in
> without the default IR symbols (CONFIG_DVB_USB_AF9005_REMOTE).
> Due to the IR related pointers beeing NULL by default, IR support will then be disabled.
> 
> The downside of this solution is, that it will no longer be possible to
> compile custom IR symbols (not using CONFIG_DVB_USB_AF9005_REMOTE) in.
> 
> Please note that this patch has NOT been tested with all possible cases.
> I don't have the hardware and could only verify that it fixes the reported
> bug.
> 
> Reported-by: Fengguag Wu <fengguang.wu@intel.com>
> Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
> Cc: <stable@vger.kernel.org>

Acked-by: Luca Olivetti <luca@ventoso.org>


> ---
>  drivers/media/usb/dvb-usb/af9005.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/usb/dvb-usb/af9005.c b/drivers/media/usb/dvb-usb/af9005.c
> index af176b6..e6d3561 100644
> --- a/drivers/media/usb/dvb-usb/af9005.c
> +++ b/drivers/media/usb/dvb-usb/af9005.c
> @@ -1081,9 +1081,12 @@ static int __init af9005_usb_module_init(void)
>  		err("usb_register failed. (%d)", result);
>  		return result;
>  	}
> +#if IS_MODULE(CONFIG_DVB_USB_AF9005) || defined(CONFIG_DVB_USB_AF9005_REMOTE)
> +	/* FIXME: convert to todays kernel IR infrastructure */
>  	rc_decode = symbol_request(af9005_rc_decode);
>  	rc_keys = symbol_request(rc_map_af9005_table);
>  	rc_keys_size = symbol_request(rc_map_af9005_table_size);
> +#endif
>  	if (rc_decode == NULL || rc_keys == NULL || rc_keys_size == NULL) {
>  		err("af9005_rc_decode function not found, disabling remote");
>  		af9005_properties.rc.legacy.rc_query = NULL;
>