* [PATCH v2] usb: gadget: Fix double free of device descriptor pointers @ 2021-04-21 19:47 Wesley Cheng 2021-04-22 11:01 ` Felipe Balbi 0 siblings, 1 reply; 7+ messages in thread From: Wesley Cheng @ 2021-04-21 19:47 UTC (permalink / raw) To: balbi, gregkh, peter.chen Cc: linux-usb, linux-kernel, Hemant Kumar, stable, Wesley Cheng From: Hemant Kumar <hemantk@codeaurora.org> Upon driver unbind usb_free_all_descriptors() function frees all speed descriptor pointers without setting them to NULL. In case gadget speed changes (i.e from super speed plus to super speed) after driver unbind only upto super speed descriptor pointers get populated. Super speed plus desc still holds the stale (already freed) pointer. Fix this issue by setting all descriptor pointers to NULL after freeing them in usb_free_all_descriptors(). Fixes: f5c61225cf29 ("usb: gadget: Update function for SuperSpeedPlus") cc: stable@vger.kernel.org Reviewed-by: Peter Chen <peter.chen@kernel.org> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org> --- Changes in v2: - Add Reviewed-by and Fixes tags - CC'ed stable tree drivers/usb/gadget/config.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/usb/gadget/config.c b/drivers/usb/gadget/config.c index 2d11535..8bb2577 100644 --- a/drivers/usb/gadget/config.c +++ b/drivers/usb/gadget/config.c @@ -194,9 +194,13 @@ EXPORT_SYMBOL_GPL(usb_assign_descriptors); void usb_free_all_descriptors(struct usb_function *f) { usb_free_descriptors(f->fs_descriptors); + f->fs_descriptors = NULL; usb_free_descriptors(f->hs_descriptors); + f->hs_descriptors = NULL; usb_free_descriptors(f->ss_descriptors); + f->ss_descriptors = NULL; usb_free_descriptors(f->ssp_descriptors); + f->ssp_descriptors = NULL; } EXPORT_SYMBOL_GPL(usb_free_all_descriptors); -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] usb: gadget: Fix double free of device descriptor pointers 2021-04-21 19:47 [PATCH v2] usb: gadget: Fix double free of device descriptor pointers Wesley Cheng @ 2021-04-22 11:01 ` Felipe Balbi 2021-04-23 19:10 ` Wesley Cheng 0 siblings, 1 reply; 7+ messages in thread From: Felipe Balbi @ 2021-04-22 11:01 UTC (permalink / raw) To: Wesley Cheng, gregkh, peter.chen Cc: linux-usb, linux-kernel, Hemant Kumar, stable, Wesley Cheng [-- Attachment #1: Type: text/plain, Size: 753 bytes --] Hi, Wesley Cheng <wcheng@codeaurora.org> writes: > From: Hemant Kumar <hemantk@codeaurora.org> > > Upon driver unbind usb_free_all_descriptors() function frees all > speed descriptor pointers without setting them to NULL. In case > gadget speed changes (i.e from super speed plus to super speed) > after driver unbind only upto super speed descriptor pointers get > populated. Super speed plus desc still holds the stale (already > freed) pointer. Fix this issue by setting all descriptor pointers > to NULL after freeing them in usb_free_all_descriptors(). could you describe this a little better? How can one trigger this case? Is the speed demotion happening after unbinding? It's not clear how to cause this bug. -- balbi [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 857 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] usb: gadget: Fix double free of device descriptor pointers 2021-04-22 11:01 ` Felipe Balbi @ 2021-04-23 19:10 ` Wesley Cheng 2021-04-24 4:16 ` Wesley Cheng 0 siblings, 1 reply; 7+ messages in thread From: Wesley Cheng @ 2021-04-23 19:10 UTC (permalink / raw) To: Felipe Balbi, gregkh, peter.chen Cc: linux-usb, linux-kernel, Hemant Kumar, stable On 4/22/2021 4:01 AM, Felipe Balbi wrote: > > Hi, > > Wesley Cheng <wcheng@codeaurora.org> writes: > >> From: Hemant Kumar <hemantk@codeaurora.org> >> >> Upon driver unbind usb_free_all_descriptors() function frees all >> speed descriptor pointers without setting them to NULL. In case >> gadget speed changes (i.e from super speed plus to super speed) >> after driver unbind only upto super speed descriptor pointers get >> populated. Super speed plus desc still holds the stale (already >> freed) pointer. Fix this issue by setting all descriptor pointers >> to NULL after freeing them in usb_free_all_descriptors(). > > could you describe this a little better? How can one trigger this case? > Is the speed demotion happening after unbinding? It's not clear how to > cause this bug. > Hi Felipe, Internally, we have a mechanism to switch the DWC3 core maximum speed parameter dynamically for displayport use cases. This issue happens whenever we have a maximum speed change occur on the USB gadget, which for DWC3 happens whenever we call gadget init. When we switch in and out of host mode, gadget init is being executed, leading to the change in the USB gadget max speed parameter: dwc->gadget->max_speed = dwc->maximum_speed; I know that configFS gadget has the max_speed sysfs file, which is a similar mechanism, but I haven't tried to see if we can reproduce the same issue with it. Let me see if we can reproduce this with that configfs speed setting. Thanks Wesley Cheng -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] usb: gadget: Fix double free of device descriptor pointers 2021-04-23 19:10 ` Wesley Cheng @ 2021-04-24 4:16 ` Wesley Cheng 2021-04-24 8:05 ` Felipe Balbi 0 siblings, 1 reply; 7+ messages in thread From: Wesley Cheng @ 2021-04-24 4:16 UTC (permalink / raw) To: Felipe Balbi, gregkh, peter.chen Cc: linux-usb, linux-kernel, Hemant Kumar, stable On 4/23/2021 12:10 PM, Wesley Cheng wrote: > > > On 4/22/2021 4:01 AM, Felipe Balbi wrote: >> >> Hi, >> >> Wesley Cheng <wcheng@codeaurora.org> writes: >> >>> From: Hemant Kumar <hemantk@codeaurora.org> >>> >>> Upon driver unbind usb_free_all_descriptors() function frees all >>> speed descriptor pointers without setting them to NULL. In case >>> gadget speed changes (i.e from super speed plus to super speed) >>> after driver unbind only upto super speed descriptor pointers get >>> populated. Super speed plus desc still holds the stale (already >>> freed) pointer. Fix this issue by setting all descriptor pointers >>> to NULL after freeing them in usb_free_all_descriptors(). >> >> could you describe this a little better? How can one trigger this case? >> Is the speed demotion happening after unbinding? It's not clear how to >> cause this bug. >> > Hi Felipe, > > Internally, we have a mechanism to switch the DWC3 core maximum speed > parameter dynamically for displayport use cases. This issue happens > whenever we have a maximum speed change occur on the USB gadget, which > for DWC3 happens whenever we call gadget init. When we switch in and > out of host mode, gadget init is being executed, leading to the change > in the USB gadget max speed parameter: > > dwc->gadget->max_speed = dwc->maximum_speed; > > I know that configFS gadget has the max_speed sysfs file, which is a > similar mechanism, but I haven't tried to see if we can reproduce the > same issue with it. Let me see if we can reproduce this with that > configfs speed setting. > > Thanks > Wesley Cheng > Hi Felipe, So I tried with doing it through the configFS max_speed, but it doesn't have the same effect, as the setting done in dwc3_gadget_init() will still be assigning the composite/UDC device's maximum speed to SSP/SS. This is what the usb_assign_descriptor() uses to determine whether or not to copy the SSP and SS descriptors. So in summary, at least for a DWC3 based subsystem, the only way to reproduce it is if there is a way to dynamically switch the DWC3 core max speed parameter. Thanks Wesley Cheng -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] usb: gadget: Fix double free of device descriptor pointers 2021-04-24 4:16 ` Wesley Cheng @ 2021-04-24 8:05 ` Felipe Balbi 2021-04-24 8:37 ` Wesley Cheng 0 siblings, 1 reply; 7+ messages in thread From: Felipe Balbi @ 2021-04-24 8:05 UTC (permalink / raw) To: Wesley Cheng, gregkh, peter.chen Cc: linux-usb, linux-kernel, Hemant Kumar, stable [-- Attachment #1: Type: text/plain, Size: 2241 bytes --] Hi, Wesley Cheng <wcheng@codeaurora.org> writes: >>>> From: Hemant Kumar <hemantk@codeaurora.org> >>>> >>>> Upon driver unbind usb_free_all_descriptors() function frees all >>>> speed descriptor pointers without setting them to NULL. In case >>>> gadget speed changes (i.e from super speed plus to super speed) >>>> after driver unbind only upto super speed descriptor pointers get >>>> populated. Super speed plus desc still holds the stale (already >>>> freed) pointer. Fix this issue by setting all descriptor pointers >>>> to NULL after freeing them in usb_free_all_descriptors(). >>> >>> could you describe this a little better? How can one trigger this case? >>> Is the speed demotion happening after unbinding? It's not clear how to >>> cause this bug. >>> >> Hi Felipe, >> >> Internally, we have a mechanism to switch the DWC3 core maximum speed >> parameter dynamically for displayport use cases. This issue happens >> whenever we have a maximum speed change occur on the USB gadget, which >> for DWC3 happens whenever we call gadget init. When we switch in and >> out of host mode, gadget init is being executed, leading to the change >> in the USB gadget max speed parameter: >> >> dwc->gadget->max_speed = dwc->maximum_speed; >> >> I know that configFS gadget has the max_speed sysfs file, which is a >> similar mechanism, but I haven't tried to see if we can reproduce the >> same issue with it. Let me see if we can reproduce this with that >> configfs speed setting. >> >> Thanks >> Wesley Cheng >> > > Hi Felipe, > > So I tried with doing it through the configFS max_speed, but it doesn't > have the same effect, as the setting done in dwc3_gadget_init() will > still be assigning the composite/UDC device's maximum speed to SSP/SS. > This is what the usb_assign_descriptor() uses to determine whether or > not to copy the SSP and SS descriptors. > > So in summary, at least for a DWC3 based subsystem, the only way to > reproduce it is if there is a way to dynamically switch the DWC3 core > max speed parameter. Could it be that you have a bug in your out-of-tree changes? Perhaps there's some assumption which your changes aren't guaranteeing. -- balbi [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 857 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] usb: gadget: Fix double free of device descriptor pointers 2021-04-24 8:05 ` Felipe Balbi @ 2021-04-24 8:37 ` Wesley Cheng 2021-04-24 13:31 ` Felipe Balbi 0 siblings, 1 reply; 7+ messages in thread From: Wesley Cheng @ 2021-04-24 8:37 UTC (permalink / raw) To: Felipe Balbi, gregkh, peter.chen Cc: linux-usb, linux-kernel, Hemant Kumar, stable On 4/24/2021 1:05 AM, Felipe Balbi wrote: > > Hi, > > Wesley Cheng <wcheng@codeaurora.org> writes: >>>>> From: Hemant Kumar <hemantk@codeaurora.org> >>>>> >>>>> Upon driver unbind usb_free_all_descriptors() function frees all >>>>> speed descriptor pointers without setting them to NULL. In case >>>>> gadget speed changes (i.e from super speed plus to super speed) >>>>> after driver unbind only upto super speed descriptor pointers get >>>>> populated. Super speed plus desc still holds the stale (already >>>>> freed) pointer. Fix this issue by setting all descriptor pointers >>>>> to NULL after freeing them in usb_free_all_descriptors(). >>>> >>>> could you describe this a little better? How can one trigger this case? >>>> Is the speed demotion happening after unbinding? It's not clear how to >>>> cause this bug. >>>> >>> Hi Felipe, >>> >>> Internally, we have a mechanism to switch the DWC3 core maximum speed >>> parameter dynamically for displayport use cases. This issue happens >>> whenever we have a maximum speed change occur on the USB gadget, which >>> for DWC3 happens whenever we call gadget init. When we switch in and >>> out of host mode, gadget init is being executed, leading to the change >>> in the USB gadget max speed parameter: >>> >>> dwc->gadget->max_speed = dwc->maximum_speed; >>> >>> I know that configFS gadget has the max_speed sysfs file, which is a >>> similar mechanism, but I haven't tried to see if we can reproduce the >>> same issue with it. Let me see if we can reproduce this with that >>> configfs speed setting. >>> >>> Thanks >>> Wesley Cheng >>> >> >> Hi Felipe, >> >> So I tried with doing it through the configFS max_speed, but it doesn't >> have the same effect, as the setting done in dwc3_gadget_init() will >> still be assigning the composite/UDC device's maximum speed to SSP/SS. >> This is what the usb_assign_descriptor() uses to determine whether or >> not to copy the SSP and SS descriptors. >> >> So in summary, at least for a DWC3 based subsystem, the only way to >> reproduce it is if there is a way to dynamically switch the DWC3 core >> max speed parameter. > > Could it be that you have a bug in your out-of-tree changes? Perhaps > there's some assumption which your changes aren't guaranteeing. > Hi Felipe, Unless there is a limitation on how the USB gadget max speed can be used, i.e. the USB gadget max speed MUST stay the same throughout a device's boot period, then our out of tree changes may have the wrong assumptions. However, I don't see that stated anywhere, and I still feel the current usb_assign_descriptors() and usb_free_all_descriptors() aren't aligned with one another. One API decides which descriptors to copy based on a parameter, whereas the other just frees all of them irrespective. Thanks Wesley Cheng -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] usb: gadget: Fix double free of device descriptor pointers 2021-04-24 8:37 ` Wesley Cheng @ 2021-04-24 13:31 ` Felipe Balbi 0 siblings, 0 replies; 7+ messages in thread From: Felipe Balbi @ 2021-04-24 13:31 UTC (permalink / raw) To: Wesley Cheng, gregkh, peter.chen Cc: linux-usb, linux-kernel, Hemant Kumar, stable [-- Attachment #1: Type: text/plain, Size: 3102 bytes --] Hi, Wesley Cheng <wcheng@codeaurora.org> writes: > On 4/24/2021 1:05 AM, Felipe Balbi wrote: >> >> Hi, >> >> Wesley Cheng <wcheng@codeaurora.org> writes: >>>>>> From: Hemant Kumar <hemantk@codeaurora.org> >>>>>> >>>>>> Upon driver unbind usb_free_all_descriptors() function frees all >>>>>> speed descriptor pointers without setting them to NULL. In case >>>>>> gadget speed changes (i.e from super speed plus to super speed) >>>>>> after driver unbind only upto super speed descriptor pointers get >>>>>> populated. Super speed plus desc still holds the stale (already >>>>>> freed) pointer. Fix this issue by setting all descriptor pointers >>>>>> to NULL after freeing them in usb_free_all_descriptors(). >>>>> >>>>> could you describe this a little better? How can one trigger this case? >>>>> Is the speed demotion happening after unbinding? It's not clear how to >>>>> cause this bug. >>>>> >>>> Hi Felipe, >>>> >>>> Internally, we have a mechanism to switch the DWC3 core maximum speed >>>> parameter dynamically for displayport use cases. This issue happens >>>> whenever we have a maximum speed change occur on the USB gadget, which >>>> for DWC3 happens whenever we call gadget init. When we switch in and >>>> out of host mode, gadget init is being executed, leading to the change >>>> in the USB gadget max speed parameter: >>>> >>>> dwc->gadget->max_speed = dwc->maximum_speed; >>>> >>>> I know that configFS gadget has the max_speed sysfs file, which is a >>>> similar mechanism, but I haven't tried to see if we can reproduce the >>>> same issue with it. Let me see if we can reproduce this with that >>>> configfs speed setting. >>>> >>>> Thanks >>>> Wesley Cheng >>>> >>> >>> Hi Felipe, >>> >>> So I tried with doing it through the configFS max_speed, but it doesn't >>> have the same effect, as the setting done in dwc3_gadget_init() will >>> still be assigning the composite/UDC device's maximum speed to SSP/SS. >>> This is what the usb_assign_descriptor() uses to determine whether or >>> not to copy the SSP and SS descriptors. >>> >>> So in summary, at least for a DWC3 based subsystem, the only way to >>> reproduce it is if there is a way to dynamically switch the DWC3 core >>> max speed parameter. >> >> Could it be that you have a bug in your out-of-tree changes? Perhaps >> there's some assumption which your changes aren't guaranteeing. >> > Hi Felipe, > > Unless there is a limitation on how the USB gadget max speed can be > used, i.e. the USB gadget max speed MUST stay the same throughout a > device's boot period, then our out of tree changes may have the wrong no, not throughout boot, but it can't change while the device is enumerated. > assumptions. However, I don't see that stated anywhere, and I still > feel the current usb_assign_descriptors() and usb_free_all_descriptors() > aren't aligned with one another. One API decides which descriptors to > copy based on a parameter, whereas the other just frees all of them > irrespective. that's a valid point. -- balbi [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 857 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2021-04-24 13:31 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-04-21 19:47 [PATCH v2] usb: gadget: Fix double free of device descriptor pointers Wesley Cheng 2021-04-22 11:01 ` Felipe Balbi 2021-04-23 19:10 ` Wesley Cheng 2021-04-24 4:16 ` Wesley Cheng 2021-04-24 8:05 ` Felipe Balbi 2021-04-24 8:37 ` Wesley Cheng 2021-04-24 13:31 ` Felipe Balbi
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