RE: [PATCH] usb: gadget: composite: Fix null pointer exception
From: 胡启航(Nick Hu)
Date: Mon Nov 01 2021 - 23:59:22 EST
> -----Original Message-----
> From: Peter Chen <peter.chen@xxxxxxxxxx>
> Sent: Monday, November 1, 2021 9:19 PM
> To: 胡启航(Nick Hu) <huqihang@xxxxxxxx>
> Cc: balbi@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] usb: gadget: composite: Fix null pointer exception
>
> On 21-11-01 09:57:57, Qihang Hu wrote:
> > In the config_ep_by_speed_and_alt function, select the corresponding
> > descriptor through g->speed, but the interface driver
>
> function driver
>
> > may not
> > support the corresponding speed. So, we need to check whether the
> > interface driver provides the corresponding speed descriptor when
> > selecting the descriptor.
> >
> > [ 237.708146] android_work: sent uevent USB_STATE=CONNECTED
> > [ 237.712464] kconfigfs-gadget gadget: super-speed config #1: b
> > [ 237.712487] kUnable to handle kernel NULL pointer dereference at
> virtual address 0000000000000000
> > [ 237.712493] kMem abort info:
> > [ 237.712498] k ESR = 0x96000006
> > [ 237.712504] k EC = 0x25: DABT (current EL), IL = 32 bits
> > [ 237.712510] k SET = 0, FnV = 0
> > [ 237.712515] k EA = 0, S1PTW = 0
> > [ 237.712520] kData abort info:
> > [ 237.712525] k ISV = 0, ISS = 0x00000006
> > [ 237.712530] k CM = 0, WnR = 0
> > [ 237.712536] kuser pgtable: 4k pages, 39-bit VAs,
> pgdp=000000020ef29000
> > [ 237.712541] k[0000000000000000] pgd=000000020ef2a003,
> pud=000000020ef2a003, pmd=0000000000000000
> > [ 237.712554] kInternal error: Oops: 96000006 [#1] PREEMPT SMP
> > [ 237.722067] kSkip md ftrace buffer dump for: 0x1609e0
> > [ 237.787037] kWorkqueue: dwc_wq dwc3_bh_work.cfi_jt
> > [ 237.854922] kpstate: 60c00085 (nZCv daIf +PAN +UAO)
> > [ 237.863165] kpc : config_ep_by_speed_and_alt+0x90/0x308
> > [ 237.871766] klr : audio_set_alt+0x54/0x78
> > [ 237.879108] ksp : ffffffc0104839e0
> >
> > Signed-off-by: Qihang Hu <huqihang@xxxxxxxx>
> > ---
> > drivers/usb/gadget/composite.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> > index 72a9797dbbae..443a65af98af 100644
> > --- a/drivers/usb/gadget/composite.c
> > +++ b/drivers/usb/gadget/composite.c
> > @@ -166,21 +166,21 @@ int config_ep_by_speed_and_alt(struct usb_gadget
> *g,
> > /* select desired speed */
> > switch (g->speed) {
> > case USB_SPEED_SUPER_PLUS:
> > - if (gadget_is_superspeed_plus(g)) {
> > + if (gadget_is_superspeed_plus(g) && f->ssp_descriptors) {
> > speed_desc = f->ssp_descriptors;
> > want_comp_desc = 1;
> > break;
> > }
> > fallthrough;
> > case USB_SPEED_SUPER:
> > - if (gadget_is_superspeed(g)) {
> > + if (gadget_is_superspeed(g) && f->ss_descriptors) {
> > speed_desc = f->ss_descriptors;
> > want_comp_desc = 1;
> > break;
> > }
> > fallthrough;
> > case USB_SPEED_HIGH:
> > - if (gadget_is_dualspeed(g)) {
> > + if (gadget_is_dualspeed(g) && f->hs_descriptors) {
> > speed_desc = f->hs_descriptors;
> > break;
> > }
> > --
> > 2.25.1
> >
>
> Besides your fix, you may show an warning that said "the function
> doesn't hold the descriptors for supported speed, using the default (FS)
> descriptors". See below kernel doc for detail.
>
> /**
> * config_ep_by_speed_and_alt() - configures the given endpoint
> *
> * ....
> * Note: the supplied function should hold all the descriptors
> * for supported speeds
> */
>
> What's more, you may fix android f_audio_source.c, and let it support
> super speed and super speed plus.
>
> --
>
> Thanks,
> Peter Chen
From 9b8262792b6e85e6060601dbfc651b1e75b649f0 Mon Sep 17 00:00:00 2001
From: Qihang Hu <huqihang@xxxxxxxx>
Date: Sat, 30 Oct 2021 16:11:38 +0800
Subject: [PATCH] usb: gadget: composite: Fix null pointer exception
In the config_ep_by_speed_and_alt function, select the corresponding
descriptor through g->speed, but the function driver may not
support the corresponding speed. So, we need to check whether the
function driver provides the corresponding speed descriptor when
selecting the descriptor.
[ 237.708146] android_work: sent uevent USB_STATE=CONNECTED
[ 237.712464] kconfigfs-gadget gadget: super-speed config #1: b
[ 237.712487] kUnable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[ 237.712493] kMem abort info:
[ 237.712498] k ESR = 0x96000006
[ 237.712504] k EC = 0x25: DABT (current EL), IL = 32 bits
[ 237.712510] k SET = 0, FnV = 0
[ 237.712515] k EA = 0, S1PTW = 0
[ 237.712520] kData abort info:
[ 237.712525] k ISV = 0, ISS = 0x00000006
[ 237.712530] k CM = 0, WnR = 0
[ 237.712536] kuser pgtable: 4k pages, 39-bit VAs, pgdp=000000020ef29000
[ 237.712541] k[0000000000000000] pgd=000000020ef2a003, pud=000000020ef2a003, pmd=0000000000000000
[ 237.712554] kInternal error: Oops: 96000006 [#1] PREEMPT SMP
[ 237.722067] kSkip md ftrace buffer dump for: 0x1609e0
[ 237.787037] kWorkqueue: dwc_wq dwc3_bh_work.cfi_jt
[ 237.854922] kpstate: 60c00085 (nZCv daIf +PAN +UAO)
[ 237.863165] kpc : config_ep_by_speed_and_alt+0x90/0x308
[ 237.871766] klr : audio_set_alt+0x54/0x78
[ 237.879108] ksp : ffffffc0104839e0
Signed-off-by: Qihang Hu <huqihang@xxxxxxxx>
---
drivers/usb/gadget/composite.c | 39 ++++++++++++++++++++++------------
1 file changed, 26 insertions(+), 13 deletions(-)
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 72a9797dbbae..4f0d81f561ae 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -151,9 +151,11 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g,
struct usb_ep *_ep,
u8 alt)
{
+ struct usb_composite_dev *cdev;
struct usb_endpoint_descriptor *chosen_desc = NULL;
struct usb_interface_descriptor *int_desc = NULL;
struct usb_descriptor_header **speed_desc = NULL;
+ int incomplete_desc = 0;
struct usb_ss_ep_comp_descriptor *comp_desc = NULL;
int want_comp_desc = 0;
@@ -167,28 +169,43 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g,
switch (g->speed) {
case USB_SPEED_SUPER_PLUS:
if (gadget_is_superspeed_plus(g)) {
- speed_desc = f->ssp_descriptors;
- want_comp_desc = 1;
- break;
+ if (f->ssp_descriptors) {
+ speed_desc = f->ssp_descriptors;
+ want_comp_desc = 1;
+ break;
+ }
+ incomplete_desc = 1;
}
fallthrough;
case USB_SPEED_SUPER:
if (gadget_is_superspeed(g)) {
- speed_desc = f->ss_descriptors;
- want_comp_desc = 1;
- break;
+ if (f->ss_descriptors) {
+ speed_desc = f->ss_descriptors;
+ want_comp_desc = 1;
+ break;
+ }
+ incomplete_desc = 1;
}
fallthrough;
case USB_SPEED_HIGH:
if (gadget_is_dualspeed(g)) {
- speed_desc = f->hs_descriptors;
- break;
+ if (f->hs_descriptors) {
+ speed_desc = f->hs_descriptors;
+ break;
+ }
+ incomplete_desc = 1;
}
fallthrough;
default:
speed_desc = f->fs_descriptors;
}
+ cdev = get_gadget_data(g);
+ if (incomplete_desc != 0)
+ WARNING(cdev,
+ "%s function doesn't hold all the descriptors for supported speep\n",
+ f->name);
+
/* find correct alternate setting descriptor */
for_each_desc(speed_desc, d_spd, USB_DT_INTERFACE) {
int_desc = (struct usb_interface_descriptor *)*d_spd;
@@ -244,12 +261,8 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g,
_ep->maxburst = comp_desc->bMaxBurst + 1;
break;
default:
- if (comp_desc->bMaxBurst != 0) {
- struct usb_composite_dev *cdev;
-
- cdev = get_gadget_data(g);
+ if (comp_desc->bMaxBurst != 0)
ERROR(cdev, "ep0 bMaxBurst must be 0\n");
- }
_ep->maxburst = 1;
break;
}
--
2.25.1
Thanks for your suggestion, this is my revised patch.
Of course, I will continue to fix android f_audio_source.c to solve the problem fundamentally.
Thanks