Linux-USB Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH] usb: gadget: udc: core: Fix error case while binding pending gadget drivers
@ 2019-08-21 10:12 Roger Quadros
  2019-08-21 14:30 ` Alan Stern
  2019-08-22 13:40 ` [PATCH v2] usb: gadget: udc: core: Fix segfault if udc_bind_to_driver() for pending driver fails Roger Quadros
  0 siblings, 2 replies; 5+ messages in thread
From: Roger Quadros @ 2019-08-21 10:12 UTC (permalink / raw)
  To: balbi, stern; +Cc: gregkh, linux-usb, linux-kernel, Roger Quadros

If binding a pending gadget driver fails we should not
remove it from the pending driver list, otherwise it
will cause a segmentation fault later when the gadget driver is
unloaded.

Test case:

- Make sure no UDC is available
- modprobe g_mass_storage file=wrongfile
- Load UDC driver so it becomes available
	lun0: unable to open backing file: wrongfile
- modprobe -r g_mass_storage

[   60.900431] Unable to handle kernel paging request at virtual address dead000000000108
[   60.908346] Mem abort info:
[   60.911145]   ESR = 0x96000044
[   60.914227]   Exception class = DABT (current EL), IL = 32 bits
[   60.920162]   SET = 0, FnV = 0
[   60.923217]   EA = 0, S1PTW = 0
[   60.926354] Data abort info:
[   60.929228]   ISV = 0, ISS = 0x00000044
[   60.933058]   CM = 0, WnR = 1
[   60.936011] [dead000000000108] address between user and kernel address ranges
[   60.943136] Internal error: Oops: 96000044 [#1] PREEMPT SMP
[   60.948691] Modules linked in: g_mass_storage(-) usb_f_mass_storage libcomposite xhci_plat_hcd xhci_hcd usbcore ti_am335x_adc kfifo_buf omap_rng cdns3 rng_core udc_core crc32_ce xfrm_user crct10dif_ce snd_so6
[   60.993995] Process modprobe (pid: 834, stack limit = 0x00000000c2aebc69)
[   61.000765] CPU: 0 PID: 834 Comm: modprobe Not tainted 4.19.59-01963-g065f42a60499 #92
[   61.008658] Hardware name: Texas Instruments SoC (DT)
[   61.014472] pstate: 60000005 (nZCv daif -PAN -UAO)
[   61.019253] pc : usb_gadget_unregister_driver+0x7c/0x108 [udc_core]
[   61.025503] lr : usb_gadget_unregister_driver+0x30/0x108 [udc_core]
[   61.031750] sp : ffff00001338fda0
[   61.035049] x29: ffff00001338fda0 x28: ffff800846d40000
[   61.040346] x27: 0000000000000000 x26: 0000000000000000
[   61.045642] x25: 0000000056000000 x24: 0000000000000800
[   61.050938] x23: ffff000008d7b0d0 x22: ffff0000088b07c8
[   61.056234] x21: ffff000001100000 x20: ffff000002020260
[   61.061530] x19: ffff0000010ffd28 x18: 0000000000000000
[   61.066825] x17: 0000000000000000 x16: 0000000000000000
[   61.072121] x15: 0000000000000000 x14: 0000000000000000
[   61.077417] x13: ffff000000000000 x12: ffffffffffffffff
[   61.082712] x11: 0000000000000030 x10: 7f7f7f7f7f7f7f7f
[   61.088008] x9 : fefefefefefefeff x8 : 0000000000000000
[   61.093304] x7 : ffffffffffffffff x6 : 000000000000ffff
[   61.098599] x5 : 8080000000000000 x4 : 0000000000000000
[   61.103895] x3 : ffff000001100020 x2 : ffff800846d40000
[   61.109190] x1 : dead000000000100 x0 : dead000000000200
[   61.114486] Call trace:
[   61.116922]  usb_gadget_unregister_driver+0x7c/0x108 [udc_core]
[   61.122828]  usb_composite_unregister+0x10/0x18 [libcomposite]
[   61.128643]  msg_cleanup+0x18/0xfce0 [g_mass_storage]
[   61.133682]  __arm64_sys_delete_module+0x17c/0x1f0
[   61.138458]  el0_svc_common+0x90/0x158
[   61.142192]  el0_svc_handler+0x2c/0x80
[   61.145926]  el0_svc+0x8/0xc
[   61.148794] Code: eb03003f d10be033 54ffff21 a94d0281 (f9000420)
[   61.154869] ---[ end trace afb22e9b637bd9a7 ]---
Segmentation fault

Signed-off-by: Roger Quadros <rogerq@ti.com>
---
 drivers/usb/gadget/udc/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 7cf34beb50df..c272c8014772 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1142,7 +1142,7 @@ static int check_pending_gadget_drivers(struct usb_udc *udc)
 		if (!driver->udc_name || strcmp(driver->udc_name,
 						dev_name(&udc->dev)) == 0) {
 			ret = udc_bind_to_driver(udc, driver);
-			if (ret != -EPROBE_DEFER)
+			if (!ret)
 				list_del(&driver->pending);
 			break;
 		}
-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] usb: gadget: udc: core: Fix error case while binding pending gadget drivers
  2019-08-21 10:12 [PATCH] usb: gadget: udc: core: Fix error case while binding pending gadget drivers Roger Quadros
@ 2019-08-21 14:30 ` Alan Stern
  2019-08-22 13:37   ` Roger Quadros
  2019-08-22 13:40 ` [PATCH v2] usb: gadget: udc: core: Fix segfault if udc_bind_to_driver() for pending driver fails Roger Quadros
  1 sibling, 1 reply; 5+ messages in thread
From: Alan Stern @ 2019-08-21 14:30 UTC (permalink / raw)
  To: Roger Quadros; +Cc: balbi, gregkh, linux-usb, linux-kernel

On Wed, 21 Aug 2019, Roger Quadros wrote:

> If binding a pending gadget driver fails we should not
> remove it from the pending driver list, otherwise it
> will cause a segmentation fault later when the gadget driver is
> unloaded.

> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
>  drivers/usb/gadget/udc/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 7cf34beb50df..c272c8014772 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1142,7 +1142,7 @@ static int check_pending_gadget_drivers(struct usb_udc *udc)
>  		if (!driver->udc_name || strcmp(driver->udc_name,
>  						dev_name(&udc->dev)) == 0) {
>  			ret = udc_bind_to_driver(udc, driver);
> -			if (ret != -EPROBE_DEFER)
> +			if (!ret)
>  				list_del(&driver->pending);
>  			break;
>  		}

This is kind of a policy question.  If binding a pending gadget driver 
fails, should the driver remain pending?

Depending on the answer to this question, you might want to change the 
list_del to list_del_init.  That should fix the segmentation fault 
just as well.

Alan Stern


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] usb: gadget: udc: core: Fix error case while binding pending gadget drivers
  2019-08-21 14:30 ` Alan Stern
@ 2019-08-22 13:37   ` Roger Quadros
  0 siblings, 0 replies; 5+ messages in thread
From: Roger Quadros @ 2019-08-22 13:37 UTC (permalink / raw)
  To: Alan Stern; +Cc: balbi, gregkh, linux-usb, linux-kernel



On 21/08/2019 17:30, Alan Stern wrote:
> On Wed, 21 Aug 2019, Roger Quadros wrote:
> 
>> If binding a pending gadget driver fails we should not
>> remove it from the pending driver list, otherwise it
>> will cause a segmentation fault later when the gadget driver is
>> unloaded.
> 
>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>> ---
>>  drivers/usb/gadget/udc/core.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
>> index 7cf34beb50df..c272c8014772 100644
>> --- a/drivers/usb/gadget/udc/core.c
>> +++ b/drivers/usb/gadget/udc/core.c
>> @@ -1142,7 +1142,7 @@ static int check_pending_gadget_drivers(struct usb_udc *udc)
>>  		if (!driver->udc_name || strcmp(driver->udc_name,
>>  						dev_name(&udc->dev)) == 0) {
>>  			ret = udc_bind_to_driver(udc, driver);
>> -			if (ret != -EPROBE_DEFER)
>> +			if (!ret)
>>  				list_del(&driver->pending);
>>  			break;
>>  		}
> 
> This is kind of a policy question.  If binding a pending gadget driver 
> fails, should the driver remain pending?
> 
> Depending on the answer to this question, you might want to change the 
> list_del to list_del_init.  That should fix the segmentation fault 
> just as well.

OK. I'll send a revised patch to retain existing policy.

cheers,
-roger
-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH v2] usb: gadget: udc: core: Fix segfault if udc_bind_to_driver() for pending driver fails
  2019-08-21 10:12 [PATCH] usb: gadget: udc: core: Fix error case while binding pending gadget drivers Roger Quadros
  2019-08-21 14:30 ` Alan Stern
@ 2019-08-22 13:40 ` Roger Quadros
  2019-08-22 14:43   ` Alan Stern
  1 sibling, 1 reply; 5+ messages in thread
From: Roger Quadros @ 2019-08-22 13:40 UTC (permalink / raw)
  To: balbi, stern; +Cc: gregkh, linux-usb, linux-kernel, Roger Quadros

If a gadget driver is in the pending drivers list, a UDC
becomes available and udc_bind_to_driver() fails, then it
gets deleted from the pending list.
i.e. list_del(&driver->pending) in check_pending_gadget_drivers().

Then if that gadget driver is unregistered,
usb_gadget_unregister_driver() does a list_del(&driver->pending)
again thus causing a page fault as that list entry has been poisoned
by the previous list_del().

Fix this by using list_del_init() instead of list_del() in
check_pending_gadget_drivers().

Test case:

- Make sure no UDC is available
- modprobe g_mass_storage file=wrongfile
- Load UDC driver so it becomes available
	lun0: unable to open backing file: wrongfile
- modprobe -r g_mass_storage

[   60.900431] Unable to handle kernel paging request at virtual address dead000000000108
[   60.908346] Mem abort info:
[   60.911145]   ESR = 0x96000044
[   60.914227]   Exception class = DABT (current EL), IL = 32 bits
[   60.920162]   SET = 0, FnV = 0
[   60.923217]   EA = 0, S1PTW = 0
[   60.926354] Data abort info:
[   60.929228]   ISV = 0, ISS = 0x00000044
[   60.933058]   CM = 0, WnR = 1
[   60.936011] [dead000000000108] address between user and kernel address ranges
[   60.943136] Internal error: Oops: 96000044 [#1] PREEMPT SMP
[   60.948691] Modules linked in: g_mass_storage(-) usb_f_mass_storage libcomposite xhci_plat_hcd xhci_hcd usbcore ti_am335x_adc kfifo_buf omap_rng cdns3 rng_core udc_core crc32_ce xfrm_user crct10dif_ce snd_so6
[   60.993995] Process modprobe (pid: 834, stack limit = 0x00000000c2aebc69)
[   61.000765] CPU: 0 PID: 834 Comm: modprobe Not tainted 4.19.59-01963-g065f42a60499 #92
[   61.008658] Hardware name: Texas Instruments SoC (DT)
[   61.014472] pstate: 60000005 (nZCv daif -PAN -UAO)
[   61.019253] pc : usb_gadget_unregister_driver+0x7c/0x108 [udc_core]
[   61.025503] lr : usb_gadget_unregister_driver+0x30/0x108 [udc_core]
[   61.031750] sp : ffff00001338fda0
[   61.035049] x29: ffff00001338fda0 x28: ffff800846d40000
[   61.040346] x27: 0000000000000000 x26: 0000000000000000
[   61.045642] x25: 0000000056000000 x24: 0000000000000800
[   61.050938] x23: ffff000008d7b0d0 x22: ffff0000088b07c8
[   61.056234] x21: ffff000001100000 x20: ffff000002020260
[   61.061530] x19: ffff0000010ffd28 x18: 0000000000000000
[   61.066825] x17: 0000000000000000 x16: 0000000000000000
[   61.072121] x15: 0000000000000000 x14: 0000000000000000
[   61.077417] x13: ffff000000000000 x12: ffffffffffffffff
[   61.082712] x11: 0000000000000030 x10: 7f7f7f7f7f7f7f7f
[   61.088008] x9 : fefefefefefefeff x8 : 0000000000000000
[   61.093304] x7 : ffffffffffffffff x6 : 000000000000ffff
[   61.098599] x5 : 8080000000000000 x4 : 0000000000000000
[   61.103895] x3 : ffff000001100020 x2 : ffff800846d40000
[   61.109190] x1 : dead000000000100 x0 : dead000000000200
[   61.114486] Call trace:
[   61.116922]  usb_gadget_unregister_driver+0x7c/0x108 [udc_core]
[   61.122828]  usb_composite_unregister+0x10/0x18 [libcomposite]
[   61.128643]  msg_cleanup+0x18/0xfce0 [g_mass_storage]
[   61.133682]  __arm64_sys_delete_module+0x17c/0x1f0
[   61.138458]  el0_svc_common+0x90/0x158
[   61.142192]  el0_svc_handler+0x2c/0x80
[   61.145926]  el0_svc+0x8/0xc
[   61.148794] Code: eb03003f d10be033 54ffff21 a94d0281 (f9000420)
[   61.154869] ---[ end trace afb22e9b637bd9a7 ]---
Segmentation fault

Signed-off-by: Roger Quadros <rogerq@ti.com>
---
Changelog:
v2
- Retain policy behaviour if pending gadget driver fails to bind.

 drivers/usb/gadget/udc/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 7cf34beb50df..92af8dc98c3d 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1143,7 +1143,7 @@ static int check_pending_gadget_drivers(struct usb_udc *udc)
 						dev_name(&udc->dev)) == 0) {
 			ret = udc_bind_to_driver(udc, driver);
 			if (ret != -EPROBE_DEFER)
-				list_del(&driver->pending);
+				list_del_init(&driver->pending);
 			break;
 		}
 
-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH v2] usb: gadget: udc: core: Fix segfault if udc_bind_to_driver() for pending driver fails
  2019-08-22 13:40 ` [PATCH v2] usb: gadget: udc: core: Fix segfault if udc_bind_to_driver() for pending driver fails Roger Quadros
@ 2019-08-22 14:43   ` Alan Stern
  0 siblings, 0 replies; 5+ messages in thread
From: Alan Stern @ 2019-08-22 14:43 UTC (permalink / raw)
  To: Roger Quadros; +Cc: balbi, gregkh, linux-usb, linux-kernel

On Thu, 22 Aug 2019, Roger Quadros wrote:

> If a gadget driver is in the pending drivers list, a UDC
> becomes available and udc_bind_to_driver() fails, then it
> gets deleted from the pending list.
> i.e. list_del(&driver->pending) in check_pending_gadget_drivers().
> 
> Then if that gadget driver is unregistered,
> usb_gadget_unregister_driver() does a list_del(&driver->pending)
> again thus causing a page fault as that list entry has been poisoned
> by the previous list_del().
> 
> Fix this by using list_del_init() instead of list_del() in
> check_pending_gadget_drivers().
> 
> Test case:
> 
> - Make sure no UDC is available
> - modprobe g_mass_storage file=wrongfile
> - Load UDC driver so it becomes available
> 	lun0: unable to open backing file: wrongfile
> - modprobe -r g_mass_storage
> 
> [   60.900431] Unable to handle kernel paging request at virtual address dead000000000108
> [   60.908346] Mem abort info:
> [   60.911145]   ESR = 0x96000044
> [   60.914227]   Exception class = DABT (current EL), IL = 32 bits
> [   60.920162]   SET = 0, FnV = 0
> [   60.923217]   EA = 0, S1PTW = 0
> [   60.926354] Data abort info:
> [   60.929228]   ISV = 0, ISS = 0x00000044
> [   60.933058]   CM = 0, WnR = 1
> [   60.936011] [dead000000000108] address between user and kernel address ranges
> [   60.943136] Internal error: Oops: 96000044 [#1] PREEMPT SMP
> [   60.948691] Modules linked in: g_mass_storage(-) usb_f_mass_storage libcomposite xhci_plat_hcd xhci_hcd usbcore ti_am335x_adc kfifo_buf omap_rng cdns3 rng_core udc_core crc32_ce xfrm_user crct10dif_ce snd_so6
> [   60.993995] Process modprobe (pid: 834, stack limit = 0x00000000c2aebc69)
> [   61.000765] CPU: 0 PID: 834 Comm: modprobe Not tainted 4.19.59-01963-g065f42a60499 #92
> [   61.008658] Hardware name: Texas Instruments SoC (DT)
> [   61.014472] pstate: 60000005 (nZCv daif -PAN -UAO)
> [   61.019253] pc : usb_gadget_unregister_driver+0x7c/0x108 [udc_core]
> [   61.025503] lr : usb_gadget_unregister_driver+0x30/0x108 [udc_core]
> [   61.031750] sp : ffff00001338fda0
> [   61.035049] x29: ffff00001338fda0 x28: ffff800846d40000
> [   61.040346] x27: 0000000000000000 x26: 0000000000000000
> [   61.045642] x25: 0000000056000000 x24: 0000000000000800
> [   61.050938] x23: ffff000008d7b0d0 x22: ffff0000088b07c8
> [   61.056234] x21: ffff000001100000 x20: ffff000002020260
> [   61.061530] x19: ffff0000010ffd28 x18: 0000000000000000
> [   61.066825] x17: 0000000000000000 x16: 0000000000000000
> [   61.072121] x15: 0000000000000000 x14: 0000000000000000
> [   61.077417] x13: ffff000000000000 x12: ffffffffffffffff
> [   61.082712] x11: 0000000000000030 x10: 7f7f7f7f7f7f7f7f
> [   61.088008] x9 : fefefefefefefeff x8 : 0000000000000000
> [   61.093304] x7 : ffffffffffffffff x6 : 000000000000ffff
> [   61.098599] x5 : 8080000000000000 x4 : 0000000000000000
> [   61.103895] x3 : ffff000001100020 x2 : ffff800846d40000
> [   61.109190] x1 : dead000000000100 x0 : dead000000000200
> [   61.114486] Call trace:
> [   61.116922]  usb_gadget_unregister_driver+0x7c/0x108 [udc_core]
> [   61.122828]  usb_composite_unregister+0x10/0x18 [libcomposite]
> [   61.128643]  msg_cleanup+0x18/0xfce0 [g_mass_storage]
> [   61.133682]  __arm64_sys_delete_module+0x17c/0x1f0
> [   61.138458]  el0_svc_common+0x90/0x158
> [   61.142192]  el0_svc_handler+0x2c/0x80
> [   61.145926]  el0_svc+0x8/0xc
> [   61.148794] Code: eb03003f d10be033 54ffff21 a94d0281 (f9000420)
> [   61.154869] ---[ end trace afb22e9b637bd9a7 ]---
> Segmentation fault
> 
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> Changelog:
> v2
> - Retain policy behaviour if pending gadget driver fails to bind.
> 
>  drivers/usb/gadget/udc/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 7cf34beb50df..92af8dc98c3d 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1143,7 +1143,7 @@ static int check_pending_gadget_drivers(struct usb_udc *udc)
>  						dev_name(&udc->dev)) == 0) {
>  			ret = udc_bind_to_driver(udc, driver);
>  			if (ret != -EPROBE_DEFER)
> -				list_del(&driver->pending);
> +				list_del_init(&driver->pending);
>  			break;
>  		}
>  

Acked-by: Alan Stern <stern@rowland.harvard.edu>


^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, back to index

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-21 10:12 [PATCH] usb: gadget: udc: core: Fix error case while binding pending gadget drivers Roger Quadros
2019-08-21 14:30 ` Alan Stern
2019-08-22 13:37   ` Roger Quadros
2019-08-22 13:40 ` [PATCH v2] usb: gadget: udc: core: Fix segfault if udc_bind_to_driver() for pending driver fails Roger Quadros
2019-08-22 14:43   ` Alan Stern

Linux-USB Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-usb/0 linux-usb/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-usb linux-usb/ https://lore.kernel.org/linux-usb \
		linux-usb@vger.kernel.org linux-usb@archiver.kernel.org
	public-inbox-index linux-usb


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-usb


AGPL code for this site: git clone https://public-inbox.org/ public-inbox