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 <[email protected]>
---
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
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 <[email protected]>
> ---
> 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
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 <[email protected]>
>> ---
>> 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
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 <[email protected]>
---
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
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 <[email protected]>
> ---
> 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 <[email protected]>