| Message ID | 20210706145025.25776-1-paskripkin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | media: em28xx: fix corrupted list | expand |
On 06/07/2021 16:50, Pavel Skripkin wrote: > Syzbot reported corrupted list in em28xx driver. The problem was in > non-reinitialized lists on disconnect. Since all 2 lists are global > variables and driver can be connected and disconnected many times we > should call INIT_LIST_HEAD() in .disconnect method to prevent corrupted > list entries. > > Fixes: 1a23f81b7dc3 ("V4L/DVB (9979): em28xx: move usb probe code to a proper place") > Reported-by: syzbot+a6969ef522a36d3344c9@syzkaller.appspotmail.com > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> > --- > drivers/media/usb/em28xx/em28xx-cards.c | 2 ++ > drivers/media/usb/em28xx/em28xx-core.c | 6 ++++++ > drivers/media/usb/em28xx/em28xx.h | 1 + > 3 files changed, 9 insertions(+) > > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c > index ba9292e2a587..8b1ff79c37a0 100644 > --- a/drivers/media/usb/em28xx/em28xx-cards.c > +++ b/drivers/media/usb/em28xx/em28xx-cards.c > @@ -4148,6 +4148,8 @@ static void em28xx_usb_disconnect(struct usb_interface *intf) > dev->dev_next = NULL; > } > kref_put(&dev->ref, em28xx_free_device); > + > + em28xx_reset_lists(); > } > > static int em28xx_usb_suspend(struct usb_interface *intf, > diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c > index 584fa400cd7d..03970ed00dba 100644 > --- a/drivers/media/usb/em28xx/em28xx-core.c > +++ b/drivers/media/usb/em28xx/em28xx-core.c > @@ -1131,6 +1131,12 @@ void em28xx_init_extension(struct em28xx *dev) > mutex_unlock(&em28xx_devlist_mutex); > } > > +void em28xx_reset_lists(void) > +{ > + INIT_LIST_HEAD(&em28xx_devlist); > + INIT_LIST_HEAD(&em28xx_extension_devlist); This needs a mutex_lock(&em28xx_devlist_mutex); But actually, I don't think this is right: if there are multiple em28xx devices, then I think if you disconnect one, then the other is - with this code - also removed from the list. Can you give a link to the actual syzbot bug? I'm not at all sure you are fixing the right thing here. Regards, Hans > +} > + > void em28xx_close_extension(struct em28xx *dev) > { > const struct em28xx_ops *ops = NULL; > diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h > index ab167cd1f400..73caaaa398d3 100644 > --- a/drivers/media/usb/em28xx/em28xx.h > +++ b/drivers/media/usb/em28xx/em28xx.h > @@ -835,6 +835,7 @@ void em28xx_stop_urbs(struct em28xx *dev); > int em28xx_set_mode(struct em28xx *dev, enum em28xx_mode set_mode); > int em28xx_gpio_set(struct em28xx *dev, const struct em28xx_reg_seq *gpio); > int em28xx_register_extension(struct em28xx_ops *dev); > +void em28xx_reset_lists(void); > void em28xx_unregister_extension(struct em28xx_ops *dev); > void em28xx_init_extension(struct em28xx *dev); > void em28xx_close_extension(struct em28xx *dev); >
On Tue, 20 Jul 2021 14:13:13 +0200 Hans Verkuil <hverkuil@xs4all.nl> wrote: > On 06/07/2021 16:50, Pavel Skripkin wrote: > > Syzbot reported corrupted list in em28xx driver. The problem was in > > non-reinitialized lists on disconnect. Since all 2 lists are global > > variables and driver can be connected and disconnected many times we > > should call INIT_LIST_HEAD() in .disconnect method to prevent > > corrupted list entries. > > > > Fixes: 1a23f81b7dc3 ("V4L/DVB (9979): em28xx: move usb probe code > > to a proper place") Reported-by: > > syzbot+a6969ef522a36d3344c9@syzkaller.appspotmail.com > > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- > > drivers/media/usb/em28xx/em28xx-cards.c | 2 ++ > > drivers/media/usb/em28xx/em28xx-core.c | 6 ++++++ > > drivers/media/usb/em28xx/em28xx.h | 1 + > > 3 files changed, 9 insertions(+) > > > > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c > > b/drivers/media/usb/em28xx/em28xx-cards.c index > > ba9292e2a587..8b1ff79c37a0 100644 --- > > a/drivers/media/usb/em28xx/em28xx-cards.c +++ > > b/drivers/media/usb/em28xx/em28xx-cards.c @@ -4148,6 +4148,8 @@ > > static void em28xx_usb_disconnect(struct usb_interface *intf) > > dev->dev_next = NULL; } > > kref_put(&dev->ref, em28xx_free_device); > > + > > + em28xx_reset_lists(); > > } > > > > static int em28xx_usb_suspend(struct usb_interface *intf, > > diff --git a/drivers/media/usb/em28xx/em28xx-core.c > > b/drivers/media/usb/em28xx/em28xx-core.c index > > 584fa400cd7d..03970ed00dba 100644 --- > > a/drivers/media/usb/em28xx/em28xx-core.c +++ > > b/drivers/media/usb/em28xx/em28xx-core.c @@ -1131,6 +1131,12 @@ > > void em28xx_init_extension(struct em28xx *dev) > > mutex_unlock(&em28xx_devlist_mutex); } > > > > +void em28xx_reset_lists(void) > > +{ > > + INIT_LIST_HEAD(&em28xx_devlist); > > + INIT_LIST_HEAD(&em28xx_extension_devlist); > > This needs a mutex_lock(&em28xx_devlist_mutex); > > But actually, I don't think this is right: if there are multiple > em28xx devices, then I think if you disconnect one, then the other is > - with this code - also removed from the list. > > Can you give a link to the actual syzbot bug? I'm not at all sure you > are fixing the right thing here. Hi, Hans! I guess, I missed my coffee that morning, sorry :) This patch looks complety wrong, of course. I've took a close look at this bug one more time, and I found the true root case of this bug. If em28xx dev has dev_next pointer we need to close dev->next extension on disconnect to avoid UAF and corrupted list bug. So, something like this should work: diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c index c1e0dccb7408..d56b040e1bd7 100644 --- a/drivers/media/usb/em28xx/em28xx-cards.c +++ b/drivers/media/usb/em28xx/em28xx-cards.c @@ -4139,8 +4139,10 @@ static void em28xx_usb_disconnect(struct usb_interface *intf) em28xx_close_extension(dev); - if (dev->dev_next) + if (dev->dev_next) { em28xx_release_resources(dev->dev_next); + em28xx_close_extension(dev->dev_next); + } em28xx_release_resources(dev); if (dev->dev_next) { How to You feel about it? I am going to send this patch for syzbot testing Syzbot link: https://syzkaller.appspot.com/bug?id=3609bbf45bf63a8f6032f330eb3d34f51cc81493 Again, sorry for v1 patch, I don't know how I came up with this fix :( With regards, Pavel Skripkin
On 21/07/2021 14:21, Pavel Skripkin wrote: > On Tue, 20 Jul 2021 14:13:13 +0200 > Hans Verkuil <hverkuil@xs4all.nl> wrote: > >> On 06/07/2021 16:50, Pavel Skripkin wrote: >>> Syzbot reported corrupted list in em28xx driver. The problem was in >>> non-reinitialized lists on disconnect. Since all 2 lists are global >>> variables and driver can be connected and disconnected many times we >>> should call INIT_LIST_HEAD() in .disconnect method to prevent >>> corrupted list entries. >>> >>> Fixes: 1a23f81b7dc3 ("V4L/DVB (9979): em28xx: move usb probe code >>> to a proper place") Reported-by: >>> syzbot+a6969ef522a36d3344c9@syzkaller.appspotmail.com >>> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- >>> drivers/media/usb/em28xx/em28xx-cards.c | 2 ++ >>> drivers/media/usb/em28xx/em28xx-core.c | 6 ++++++ >>> drivers/media/usb/em28xx/em28xx.h | 1 + >>> 3 files changed, 9 insertions(+) >>> >>> diff --git a/drivers/media/usb/em28xx/em28xx-cards.c >>> b/drivers/media/usb/em28xx/em28xx-cards.c index >>> ba9292e2a587..8b1ff79c37a0 100644 --- >>> a/drivers/media/usb/em28xx/em28xx-cards.c +++ >>> b/drivers/media/usb/em28xx/em28xx-cards.c @@ -4148,6 +4148,8 @@ >>> static void em28xx_usb_disconnect(struct usb_interface *intf) >>> dev->dev_next = NULL; } >>> kref_put(&dev->ref, em28xx_free_device); >>> + >>> + em28xx_reset_lists(); >>> } >>> >>> static int em28xx_usb_suspend(struct usb_interface *intf, >>> diff --git a/drivers/media/usb/em28xx/em28xx-core.c >>> b/drivers/media/usb/em28xx/em28xx-core.c index >>> 584fa400cd7d..03970ed00dba 100644 --- >>> a/drivers/media/usb/em28xx/em28xx-core.c +++ >>> b/drivers/media/usb/em28xx/em28xx-core.c @@ -1131,6 +1131,12 @@ >>> void em28xx_init_extension(struct em28xx *dev) >>> mutex_unlock(&em28xx_devlist_mutex); } >>> >>> +void em28xx_reset_lists(void) >>> +{ >>> + INIT_LIST_HEAD(&em28xx_devlist); >>> + INIT_LIST_HEAD(&em28xx_extension_devlist); >> >> This needs a mutex_lock(&em28xx_devlist_mutex); >> >> But actually, I don't think this is right: if there are multiple >> em28xx devices, then I think if you disconnect one, then the other is >> - with this code - also removed from the list. >> >> Can you give a link to the actual syzbot bug? I'm not at all sure you >> are fixing the right thing here. > > Hi, Hans! > > I guess, I missed my coffee that morning, sorry :) This patch looks > complety wrong, of course. > > I've took a close look at this bug one more time, and I found the true > root case of this bug. > > If em28xx dev has dev_next pointer we need to close dev->next extension > on disconnect to avoid UAF and corrupted list bug. So, something like > this should work: > > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c > index c1e0dccb7408..d56b040e1bd7 100644 > --- a/drivers/media/usb/em28xx/em28xx-cards.c > +++ b/drivers/media/usb/em28xx/em28xx-cards.c > @@ -4139,8 +4139,10 @@ static void em28xx_usb_disconnect(struct usb_interface *intf) > > em28xx_close_extension(dev); > > - if (dev->dev_next) > + if (dev->dev_next) { > em28xx_release_resources(dev->dev_next); > + em28xx_close_extension(dev->dev_next); > + } > em28xx_release_resources(dev); > > if (dev->dev_next) { > > How to You feel about it? I am going to send this patch for syzbot > testing That looks a lot saner :-) > > > Syzbot link: > https://syzkaller.appspot.com/bug?id=3609bbf45bf63a8f6032f330eb3d34f51cc81493 > > > Again, sorry for v1 patch, I don't know how I came up with this fix :( No problem, just post a v2 if syzbot passes. Regards, Hans > > > > With regards, > Pavel Skripkin >
diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c index ba9292e2a587..8b1ff79c37a0 100644 --- a/drivers/media/usb/em28xx/em28xx-cards.c +++ b/drivers/media/usb/em28xx/em28xx-cards.c @@ -4148,6 +4148,8 @@ static void em28xx_usb_disconnect(struct usb_interface *intf) dev->dev_next = NULL; } kref_put(&dev->ref, em28xx_free_device); + + em28xx_reset_lists(); } static int em28xx_usb_suspend(struct usb_interface *intf, diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c index 584fa400cd7d..03970ed00dba 100644 --- a/drivers/media/usb/em28xx/em28xx-core.c +++ b/drivers/media/usb/em28xx/em28xx-core.c @@ -1131,6 +1131,12 @@ void em28xx_init_extension(struct em28xx *dev) mutex_unlock(&em28xx_devlist_mutex); } +void em28xx_reset_lists(void) +{ + INIT_LIST_HEAD(&em28xx_devlist); + INIT_LIST_HEAD(&em28xx_extension_devlist); +} + void em28xx_close_extension(struct em28xx *dev) { const struct em28xx_ops *ops = NULL; diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h index ab167cd1f400..73caaaa398d3 100644 --- a/drivers/media/usb/em28xx/em28xx.h +++ b/drivers/media/usb/em28xx/em28xx.h @@ -835,6 +835,7 @@ void em28xx_stop_urbs(struct em28xx *dev); int em28xx_set_mode(struct em28xx *dev, enum em28xx_mode set_mode); int em28xx_gpio_set(struct em28xx *dev, const struct em28xx_reg_seq *gpio); int em28xx_register_extension(struct em28xx_ops *dev); +void em28xx_reset_lists(void); void em28xx_unregister_extension(struct em28xx_ops *dev); void em28xx_init_extension(struct em28xx *dev); void em28xx_close_extension(struct em28xx *dev);
Syzbot reported corrupted list in em28xx driver. The problem was in non-reinitialized lists on disconnect. Since all 2 lists are global variables and driver can be connected and disconnected many times we should call INIT_LIST_HEAD() in .disconnect method to prevent corrupted list entries. Fixes: 1a23f81b7dc3 ("V4L/DVB (9979): em28xx: move usb probe code to a proper place") Reported-by: syzbot+a6969ef522a36d3344c9@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- drivers/media/usb/em28xx/em28xx-cards.c | 2 ++ drivers/media/usb/em28xx/em28xx-core.c | 6 ++++++ drivers/media/usb/em28xx/em28xx.h | 1 + 3 files changed, 9 insertions(+)