# \[V2 PATCH\] usb: mtu3: fix NULL pointer dereference - Subsystems: MEDIATEK USB3 DRD IP DRIVER, THE REST, USB SUBSYSTEM - Maintainers: Chunfeng Yun, Linus Torvalds, Greg Kroah-Hartman - List: linux-arm-kernel - 7 messages, 4 authors - Page: https://ratatoskr.run/linux-arm-kernel/2020/06/6020002/t ## \[V2 PATCH\] usb: mtu3: fix NULL pointer dereference - From: Chunfeng Yun \ - Date: 2020-06-30 07:43:14 - Message: https://ratatoskr.run/linux-arm-kernel/2020/06/6020002.md ```text Some pointers are dereferenced before successful checks. Reported-by: Markus Elfring Signed-off-by: Chunfeng Yun --- v2: nothing changed, but abandon another patch --- drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c index f93732e..1689ca8 100644 --- a/drivers/usb/mtu3/mtu3_gadget.c +++ b/drivers/usb/mtu3/mtu3_gadget.c @@ -332,14 +332,21 @@ static int mtu3_gadget_queue(struct usb_ep *ep, static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req) { - struct mtu3_ep *mep = to_mtu3_ep(ep); - struct mtu3_request *mreq = to_mtu3_request(req); + struct mtu3_ep *mep; + struct mtu3_request *mreq; struct mtu3_request *r; + struct mtu3 *mtu; unsigned long flags; int ret = 0; - struct mtu3 *mtu = mep->mtu; - if (!ep || !req || mreq->mep != mep) + if (!ep || !req) + return -EINVAL; + + mep = to_mtu3_ep(ep); + mtu = mep->mtu; + + mreq = to_mtu3_request(req); + if (mreq->mep != mep) return -EINVAL; dev_dbg(mtu->dev, "%s : req=%p\n", __func__, req); @@ -373,8 +380,8 @@ static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req) */ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) { - struct mtu3_ep *mep = to_mtu3_ep(ep); - struct mtu3 *mtu = mep->mtu; + struct mtu3_ep *mep; + struct mtu3 *mtu; struct mtu3_request *mreq; unsigned long flags; int ret = 0; @@ -382,6 +389,9 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) if (!ep) return -EINVAL; + mep = to_mtu3_ep(ep); + mtu = mep->mtu; + dev_dbg(mtu->dev, "%s : %s...", __func__, ep->name); spin_lock_irqsave(&mtu->lock, flags); @@ -422,11 +432,12 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) /* Sets the halt feature with the clear requests ignored */ static int mtu3_gadget_ep_set_wedge(struct usb_ep *ep) { - struct mtu3_ep *mep = to_mtu3_ep(ep); + struct mtu3_ep *mep; if (!ep) return -EINVAL; + mep = to_mtu3_ep(ep); mep->wedged = 1; return usb_ep_set_halt(ep); -- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ``` ## Re: \[PATCH v2\] usb: mtu3: Fix NULL pointer dereferences - From: Markus Elfring \ - Date: 2020-06-30 10:47:23 - Message: https://ratatoskr.run/linux-arm-kernel/2020/06/6020182.md ```text > Some pointers are dereferenced before successful checks. I propose to reconsider and improve also this change description. * Would a null pointer dereference be possible only with the variables “mep” and “mreq” in the implementation of the function “mtu3_gadget_dequeue”? (Can it make sense to split the patch according to this detail?) * How do you think about to convert any more variable initialisations to later assignments? * Will it become helpful to add the tag “Fixes” to the commit message? … > --- > v2: nothing changed, but abandon another patch Are there chances to take any previous patch review comments better into account (besides the shown reduction of update steps)? > --- > drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++------- I suggest to replace the triple dashes before this diffstat by a blank line. Regards, Markus _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ``` ## Re: \[V2 PATCH\] usb: mtu3: fix NULL pointer dereference - From: Greg Kroah-Hartman \ - Date: 2020-07-01 11:58:37 - Message: https://ratatoskr.run/linux-arm-kernel/2020/07/6021686.md ```text On Tue, Jun 30, 2020 at 03:42:22PM +0800, Chunfeng Yun wrote: > Some pointers are dereferenced before successful checks. > > Reported-by: Markus Elfring > Signed-off-by: Chunfeng Yun > --- > v2: nothing changed, but abandon another patch > --- > drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++------- > 1 file changed, 18 insertions(+), 7 deletions(-) > > diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c > index f93732e..1689ca8 100644 > --- a/drivers/usb/mtu3/mtu3_gadget.c > +++ b/drivers/usb/mtu3/mtu3_gadget.c > @@ -332,14 +332,21 @@ static int mtu3_gadget_queue(struct usb_ep *ep, > > static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req) > { > - struct mtu3_ep *mep = to_mtu3_ep(ep); > - struct mtu3_request *mreq = to_mtu3_request(req); > + struct mtu3_ep *mep; > + struct mtu3_request *mreq; > struct mtu3_request *r; > + struct mtu3 *mtu; > unsigned long flags; > int ret = 0; > - struct mtu3 *mtu = mep->mtu; > > - if (!ep || !req || mreq->mep != mep) > + if (!ep || !req) > + return -EINVAL; How will either of those ever be NULL? The kernel will not call this function with either of them being NULL, right? > + > + mep = to_mtu3_ep(ep); > + mtu = mep->mtu; > + > + mreq = to_mtu3_request(req); > + if (mreq->mep != mep) > return -EINVAL; > > dev_dbg(mtu->dev, "%s : req=%p\n", __func__, req); > @@ -373,8 +380,8 @@ static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req) > */ > static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) > { > - struct mtu3_ep *mep = to_mtu3_ep(ep); > - struct mtu3 *mtu = mep->mtu; > + struct mtu3_ep *mep; > + struct mtu3 *mtu; > struct mtu3_request *mreq; > unsigned long flags; > int ret = 0; > @@ -382,6 +389,9 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) > if (!ep) > return -EINVAL; Same here, how can that ever happen? > > + mep = to_mtu3_ep(ep); > + mtu = mep->mtu; > + > dev_dbg(mtu->dev, "%s : %s...", __func__, ep->name); > > spin_lock_irqsave(&mtu->lock, flags); > @@ -422,11 +432,12 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) > /* Sets the halt feature with the clear requests ignored */ > static int mtu3_gadget_ep_set_wedge(struct usb_ep *ep) > { > - struct mtu3_ep *mep = to_mtu3_ep(ep); > + struct mtu3_ep *mep; > > if (!ep) > return -EINVAL; Again, same here. thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ``` ## Re: \[V2 PATCH\] usb: mtu3: fix NULL pointer dereference - From: Chunfeng Yun \ - Date: 2020-07-02 02:53:26 - Message: https://ratatoskr.run/linux-arm-kernel/2020/07/6022701.md ```text On Wed, 2020-07-01 at 13:58 +0200, Greg Kroah-Hartman wrote: > On Tue, Jun 30, 2020 at 03:42:22PM +0800, Chunfeng Yun wrote: > > Some pointers are dereferenced before successful checks. > > > > Reported-by: Markus Elfring > > Signed-off-by: Chunfeng Yun > > --- > > v2: nothing changed, but abandon another patch > > --- > > drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++------- > > 1 file changed, 18 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c > > index f93732e..1689ca8 100644 > > --- a/drivers/usb/mtu3/mtu3_gadget.c > > +++ b/drivers/usb/mtu3/mtu3_gadget.c > > @@ -332,14 +332,21 @@ static int mtu3_gadget_queue(struct usb_ep *ep, > > > > static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req) > > { > > - struct mtu3_ep *mep = to_mtu3_ep(ep); > > - struct mtu3_request *mreq = to_mtu3_request(req); > > + struct mtu3_ep *mep; > > + struct mtu3_request *mreq; > > struct mtu3_request *r; > > + struct mtu3 *mtu; > > unsigned long flags; > > int ret = 0; > > - struct mtu3 *mtu = mep->mtu; > > > > - if (!ep || !req || mreq->mep != mep) > > + if (!ep || !req) > > + return -EINVAL; > > How will either of those ever be NULL? The kernel will not call this > function with either of them being NULL, right? Yes, I find all class drivers already ensure they are not NULL. > > > + > > + mep = to_mtu3_ep(ep); > > + mtu = mep->mtu; > > + > > + mreq = to_mtu3_request(req); > > + if (mreq->mep != mep) > > return -EINVAL; > > > > dev_dbg(mtu->dev, "%s : req=%p\n", __func__, req); > > @@ -373,8 +380,8 @@ static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req) > > */ > > static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) > > { > > - struct mtu3_ep *mep = to_mtu3_ep(ep); > > - struct mtu3 *mtu = mep->mtu; > > + struct mtu3_ep *mep; > > + struct mtu3 *mtu; > > struct mtu3_request *mreq; > > unsigned long flags; > > int ret = 0; > > @@ -382,6 +389,9 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) > > if (!ep) > > return -EINVAL; > > Same here, how can that ever happen? Maybe when the class driver has something wrong:) You mean it's better to remove these unnecessary checks? Thanks > > > > > + mep = to_mtu3_ep(ep); > > + mtu = mep->mtu; > > + > > dev_dbg(mtu->dev, "%s : %s...", __func__, ep->name); > > > > spin_lock_irqsave(&mtu->lock, flags); > > @@ -422,11 +432,12 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) > > /* Sets the halt feature with the clear requests ignored */ > > static int mtu3_gadget_ep_set_wedge(struct usb_ep *ep) > > { > > - struct mtu3_ep *mep = to_mtu3_ep(ep); > > + struct mtu3_ep *mep; > > > > if (!ep) > > return -EINVAL; > > Again, same here. > > thanks, > > greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ``` ## Re: \[V2 PATCH\] usb: mtu3: fix NULL pointer dereference - From: Felipe Balbi \ - Date: 2020-07-09 06:40:22 - Message: https://ratatoskr.run/linux-arm-kernel/2020/07/6030174.md ```text Chunfeng Yun [ref] writes: > Some pointers are dereferenced before successful checks. > > Reported-by: Markus Elfring > Signed-off-by: Chunfeng Yun do you need a Fixes tag here? Perhaps a Cc stable too? -- balbi ``` ## Re: \[V2 PATCH\] usb: mtu3: fix NULL pointer dereference - From: Felipe Balbi \ - Date: 2020-07-09 06:43:07 - Message: https://ratatoskr.run/linux-arm-kernel/2020/07/6030175.md ```text Hi, Chunfeng Yun [ref] writes: >> > @@ -373,8 +380,8 @@ static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req) >> > */ >> > static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) >> > { >> > - struct mtu3_ep *mep = to_mtu3_ep(ep); >> > - struct mtu3 *mtu = mep->mtu; >> > + struct mtu3_ep *mep; >> > + struct mtu3 *mtu; >> > struct mtu3_request *mreq; >> > unsigned long flags; >> > int ret = 0; >> > @@ -382,6 +389,9 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value) >> > if (!ep) >> > return -EINVAL; >> >> Same here, how can that ever happen? > Maybe when the class driver has something wrong:) > > You mean it's better to remove these unnecessary checks? if we need those checks, I'd rather have them at a central location, such as udc/core.c. But, as Greg mentioned, the kernel doesn't call these with NULL pointers. -- balbi ``` ## Re: \[V2 PATCH\] usb: mtu3: fix NULL pointer dereference - From: Chunfeng Yun \ - Date: 2020-07-09 07:06:09 - Message: https://ratatoskr.run/linux-arm-kernel/2020/07/6030197.md ```text On Thu, 2020-07-09 at 09:40 +0300, Felipe Balbi wrote: > Chunfeng Yun [ref] writes: > > > Some pointers are dereferenced before successful checks. > > > > Reported-by: Markus Elfring > > Signed-off-by: Chunfeng Yun > > do you need a Fixes tag here? Perhaps a Cc stable too? It will not cause somes issues, I think no need add it. According to Greg's comment, I guess he means no need check these pointers at all, so I'll send a new version to remove checks. Thank you > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ```