| Message ID | 1375819848-2658-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 08/06/2013 10:10 PM, Laurent Pinchart wrote: > The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in > implementation of the mmap() and get_unmapped_area() file operations > that calls vb2_mmap() and vb2_get_unmapped_area() on the queue > associated with the video device. Neither the > vb2_fop_mmap/vb2_fop_get_unmapped_area nor the > v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any > lock, leading to race conditions between mmap/get_unmapped_area and > other buffer-related ioctls such as VIDIOC_REQBUFS. > > Fix it by taking the queue or device lock around the vb2_mmap() and > vb2_get_unmapped_area() calls. > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Thanks! Hans > --- > drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 9fc4bab..c9b50c7 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf); > int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) > { > struct video_device *vdev = video_devdata(file); > + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; > + int err; > > - return vb2_mmap(vdev->queue, vma); > + if (lock && mutex_lock_interruptible(lock)) > + return -ERESTARTSYS; > + err = vb2_mmap(vdev->queue, vma); > + if (lock) > + mutex_unlock(lock); > + return err; > } > EXPORT_SYMBOL_GPL(vb2_fop_mmap); > > @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr, > unsigned long len, unsigned long pgoff, unsigned long flags) > { > struct video_device *vdev = video_devdata(file); > + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; > + int ret; > > - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > + if (lock && mutex_lock_interruptible(lock)) > + return -ERESTARTSYS; > + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > + if (lock) > + mutex_unlock(lock); > + return ret; > } > EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area); > #endif > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Laurent, This patch caused a circular locking dependency as reported by Sasha Levin: https://lkml.org/lkml/2014/5/5/366 The reason is that copy_to/from_user is called in video_usercopy() with the core lock held. The copy functions can fault which takes the mmap_sem. If it was just video_usercopy() then it would be fairly easy to solve this, but the copy_to_/from_user functions are also called from read and write and they can be used in other unexpected places. I'm not sure if vb2_fop_get_unmapped_area() is a problem. I suspect (but I'm not sure) that when that one is called the mmap_sem isn't taken, in which case taking the lock is fine. But taking the lock in vb2_fop_mmap() does cause lockdep problems. Ideally I would like to drop taking that lock in vb2_fop_mmap and resolve the race condition that it intended to fix in a different way. Regards, Hans On 08/06/2013 10:10 PM, Laurent Pinchart wrote: > The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in > implementation of the mmap() and get_unmapped_area() file operations > that calls vb2_mmap() and vb2_get_unmapped_area() on the queue > associated with the video device. Neither the > vb2_fop_mmap/vb2_fop_get_unmapped_area nor the > v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any > lock, leading to race conditions between mmap/get_unmapped_area and > other buffer-related ioctls such as VIDIOC_REQBUFS. > > Fix it by taking the queue or device lock around the vb2_mmap() and > vb2_get_unmapped_area() calls. > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > --- > drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 9fc4bab..c9b50c7 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf); > int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) > { > struct video_device *vdev = video_devdata(file); > + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; > + int err; > > - return vb2_mmap(vdev->queue, vma); > + if (lock && mutex_lock_interruptible(lock)) > + return -ERESTARTSYS; > + err = vb2_mmap(vdev->queue, vma); > + if (lock) > + mutex_unlock(lock); > + return err; > } > EXPORT_SYMBOL_GPL(vb2_fop_mmap); > > @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr, > unsigned long len, unsigned long pgoff, unsigned long flags) > { > struct video_device *vdev = video_devdata(file); > + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; > + int ret; > > - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > + if (lock && mutex_lock_interruptible(lock)) > + return -ERESTARTSYS; > + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > + if (lock) > + mutex_unlock(lock); > + return ret; > } > EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area); > #endif > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Hans, On Friday 23 May 2014 15:54:29 Hans Verkuil wrote: > Hi Laurent, > > This patch caused a circular locking dependency as reported by Sasha Levin: > > https://lkml.org/lkml/2014/5/5/366 > > The reason is that copy_to/from_user is called in video_usercopy() with the > core lock held. The copy functions can fault which takes the mmap_sem. If it > was just video_usercopy() then it would be fairly easy to solve this, but > the copy_to_/from_user functions are also called from read and write and > they can be used in other unexpected places. > > I'm not sure if vb2_fop_get_unmapped_area() is a problem. I suspect (but I'm > not sure) that when that one is called the mmap_sem isn't taken, in which > case taking the lock is fine. > > But taking the lock in vb2_fop_mmap() does cause lockdep problems. > > Ideally I would like to drop taking that lock in vb2_fop_mmap and resolve > the race condition that it intended to fix in a different way. I'm of course fine with a different way to solve the race condition, if we can find a good one. Do you already know how you would like to solve this ? > On 08/06/2013 10:10 PM, Laurent Pinchart wrote: > > The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in > > implementation of the mmap() and get_unmapped_area() file operations > > that calls vb2_mmap() and vb2_get_unmapped_area() on the queue > > associated with the video device. Neither the > > vb2_fop_mmap/vb2_fop_get_unmapped_area nor the > > v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any > > lock, leading to race conditions between mmap/get_unmapped_area and > > other buffer-related ioctls such as VIDIOC_REQBUFS. > > > > Fix it by taking the queue or device lock around the vb2_mmap() and > > vb2_get_unmapped_area() calls. > > > > Signed-off-by: Laurent Pinchart > > <laurent.pinchart+renesas@ideasonboard.com> > > --- > > > > drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++-- > > 1 file changed, 16 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c > > b/drivers/media/v4l2-core/videobuf2-core.c index 9fc4bab..c9b50c7 100644 > > --- a/drivers/media/v4l2-core/videobuf2-core.c > > +++ b/drivers/media/v4l2-core/videobuf2-core.c > > @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf); > > > > int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) > > { > > > > struct video_device *vdev = video_devdata(file); > > > > + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev- >lock; > > + int err; > > > > - return vb2_mmap(vdev->queue, vma); > > + if (lock && mutex_lock_interruptible(lock)) > > + return -ERESTARTSYS; > > + err = vb2_mmap(vdev->queue, vma); > > + if (lock) > > + mutex_unlock(lock); > > + return err; > > > > } > > EXPORT_SYMBOL_GPL(vb2_fop_mmap); > > > > @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct file > > *file, unsigned long addr,> > > unsigned long len, unsigned long pgoff, unsigned long flags) > > > > { > > > > struct video_device *vdev = video_devdata(file); > > > > + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev- >lock; > > + int ret; > > > > - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > > + if (lock && mutex_lock_interruptible(lock)) > > + return -ERESTARTSYS; > > + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > > + if (lock) > > + mutex_unlock(lock); > > + return ret; > > > > } > > EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area); > > #endif
Ping? On 05/23/2014 09:54 AM, Hans Verkuil wrote: > Hi Laurent, > > This patch caused a circular locking dependency as reported by Sasha Levin: > > https://lkml.org/lkml/2014/5/5/366 > > The reason is that copy_to/from_user is called in video_usercopy() with the > core lock held. The copy functions can fault which takes the mmap_sem. If it > was just video_usercopy() then it would be fairly easy to solve this, but > the copy_to_/from_user functions are also called from read and write and they > can be used in other unexpected places. > > I'm not sure if vb2_fop_get_unmapped_area() is a problem. I suspect (but I'm > not sure) that when that one is called the mmap_sem isn't taken, in which > case taking the lock is fine. > > But taking the lock in vb2_fop_mmap() does cause lockdep problems. > > Ideally I would like to drop taking that lock in vb2_fop_mmap and resolve the > race condition that it intended to fix in a different way. > > Regards, > > Hans > > On 08/06/2013 10:10 PM, Laurent Pinchart wrote: >> The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in >> implementation of the mmap() and get_unmapped_area() file operations >> that calls vb2_mmap() and vb2_get_unmapped_area() on the queue >> associated with the video device. Neither the >> vb2_fop_mmap/vb2_fop_get_unmapped_area nor the >> v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any >> lock, leading to race conditions between mmap/get_unmapped_area and >> other buffer-related ioctls such as VIDIOC_REQBUFS. >> >> Fix it by taking the queue or device lock around the vb2_mmap() and >> vb2_get_unmapped_area() calls. >> >> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> >> --- >> drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++-- >> 1 file changed, 16 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c >> index 9fc4bab..c9b50c7 100644 >> --- a/drivers/media/v4l2-core/videobuf2-core.c >> +++ b/drivers/media/v4l2-core/videobuf2-core.c >> @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf); >> int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) >> { >> struct video_device *vdev = video_devdata(file); >> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; >> + int err; >> >> - return vb2_mmap(vdev->queue, vma); >> + if (lock && mutex_lock_interruptible(lock)) >> + return -ERESTARTSYS; >> + err = vb2_mmap(vdev->queue, vma); >> + if (lock) >> + mutex_unlock(lock); >> + return err; >> } >> EXPORT_SYMBOL_GPL(vb2_fop_mmap); >> >> @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr, >> unsigned long len, unsigned long pgoff, unsigned long flags) >> { >> struct video_device *vdev = video_devdata(file); >> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; >> + int ret; >> >> - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); >> + if (lock && mutex_lock_interruptible(lock)) >> + return -ERESTARTSYS; >> + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); >> + if (lock) >> + mutex_unlock(lock); >> + return ret; >> } >> EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area); >> #endif >> > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wednesday 25 June 2014 12:58:03 Sasha Levin wrote: > Ping? Hans, I've replied to your previous e-mail with I'm of course fine with a different way to solve the race condition, if we can find a good one. Do you already know how you would like to solve this ? > On 05/23/2014 09:54 AM, Hans Verkuil wrote: > > Hi Laurent, > > > > This patch caused a circular locking dependency as reported by Sasha > > Levin: > > > > https://lkml.org/lkml/2014/5/5/366 > > > > The reason is that copy_to/from_user is called in video_usercopy() with > > the > > core lock held. The copy functions can fault which takes the mmap_sem. If > > it was just video_usercopy() then it would be fairly easy to solve this, > > but the copy_to_/from_user functions are also called from read and write > > and they can be used in other unexpected places. > > > > I'm not sure if vb2_fop_get_unmapped_area() is a problem. I suspect (but > > I'm not sure) that when that one is called the mmap_sem isn't taken, in > > which case taking the lock is fine. > > > > But taking the lock in vb2_fop_mmap() does cause lockdep problems. > > > > Ideally I would like to drop taking that lock in vb2_fop_mmap and resolve > > the race condition that it intended to fix in a different way. > > > > Regards, > > > > Hans > > > > On 08/06/2013 10:10 PM, Laurent Pinchart wrote: > >> The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in > >> implementation of the mmap() and get_unmapped_area() file operations > >> that calls vb2_mmap() and vb2_get_unmapped_area() on the queue > >> associated with the video device. Neither the > >> vb2_fop_mmap/vb2_fop_get_unmapped_area nor the > >> v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any > >> lock, leading to race conditions between mmap/get_unmapped_area and > >> other buffer-related ioctls such as VIDIOC_REQBUFS. > >> > >> Fix it by taking the queue or device lock around the vb2_mmap() and > >> vb2_get_unmapped_area() calls. > >> > >> Signed-off-by: Laurent Pinchart > >> <laurent.pinchart+renesas@ideasonboard.com> > >> --- > >> > >> drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++-- > >> 1 file changed, 16 insertions(+), 2 deletions(-) > >> > >> diff --git a/drivers/media/v4l2-core/videobuf2-core.c > >> b/drivers/media/v4l2-core/videobuf2-core.c index 9fc4bab..c9b50c7 100644 > >> --- a/drivers/media/v4l2-core/videobuf2-core.c > >> +++ b/drivers/media/v4l2-core/videobuf2-core.c > >> @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf); > >> int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) > >> { > >> struct video_device *vdev = video_devdata(file); > >> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : > >> vdev->lock; > >> + int err; > >> > >> - return vb2_mmap(vdev->queue, vma); > >> + if (lock && mutex_lock_interruptible(lock)) > >> + return -ERESTARTSYS; > >> + err = vb2_mmap(vdev->queue, vma); > >> + if (lock) > >> + mutex_unlock(lock); > >> + return err; > >> } > >> EXPORT_SYMBOL_GPL(vb2_fop_mmap); > >> > >> @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct > >> file *file, unsigned long addr,>> > >> unsigned long len, unsigned long pgoff, unsigned long flags) > >> { > >> struct video_device *vdev = video_devdata(file); > >> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : > >> vdev->lock; > >> + int ret; > >> > >> - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > >> + if (lock && mutex_lock_interruptible(lock)) > >> + return -ERESTARTSYS; > >> + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); > >> + if (lock) > >> + mutex_unlock(lock); > >> + return ret; > >> > >> } > >> EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area); > >> #endif
For now it is -ENOTIME for me. It's on my TODO list, but there are a number of other things I want to finish first. Regards, Hans On 07/01/2014 11:08 PM, Laurent Pinchart wrote: > On Wednesday 25 June 2014 12:58:03 Sasha Levin wrote: >> Ping? > > Hans, I've replied to your previous e-mail with > > I'm of course fine with a different way to solve the race condition, if we can > find a good one. Do you already know how you would like to solve this ? > >> On 05/23/2014 09:54 AM, Hans Verkuil wrote: >>> Hi Laurent, >>> >>> This patch caused a circular locking dependency as reported by Sasha >>> Levin: >>> >>> https://lkml.org/lkml/2014/5/5/366 >>> >>> The reason is that copy_to/from_user is called in video_usercopy() with >>> the >>> core lock held. The copy functions can fault which takes the mmap_sem. If >>> it was just video_usercopy() then it would be fairly easy to solve this, >>> but the copy_to_/from_user functions are also called from read and write >>> and they can be used in other unexpected places. >>> >>> I'm not sure if vb2_fop_get_unmapped_area() is a problem. I suspect (but >>> I'm not sure) that when that one is called the mmap_sem isn't taken, in >>> which case taking the lock is fine. >>> >>> But taking the lock in vb2_fop_mmap() does cause lockdep problems. >>> >>> Ideally I would like to drop taking that lock in vb2_fop_mmap and resolve >>> the race condition that it intended to fix in a different way. >>> >>> Regards, >>> >>> Hans >>> >>> On 08/06/2013 10:10 PM, Laurent Pinchart wrote: >>>> The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in >>>> implementation of the mmap() and get_unmapped_area() file operations >>>> that calls vb2_mmap() and vb2_get_unmapped_area() on the queue >>>> associated with the video device. Neither the >>>> vb2_fop_mmap/vb2_fop_get_unmapped_area nor the >>>> v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any >>>> lock, leading to race conditions between mmap/get_unmapped_area and >>>> other buffer-related ioctls such as VIDIOC_REQBUFS. >>>> >>>> Fix it by taking the queue or device lock around the vb2_mmap() and >>>> vb2_get_unmapped_area() calls. >>>> >>>> Signed-off-by: Laurent Pinchart >>>> <laurent.pinchart+renesas@ideasonboard.com> >>>> --- >>>> >>>> drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++-- >>>> 1 file changed, 16 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/media/v4l2-core/videobuf2-core.c >>>> b/drivers/media/v4l2-core/videobuf2-core.c index 9fc4bab..c9b50c7 100644 >>>> --- a/drivers/media/v4l2-core/videobuf2-core.c >>>> +++ b/drivers/media/v4l2-core/videobuf2-core.c >>>> @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf); >>>> int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) >>>> { >>>> struct video_device *vdev = video_devdata(file); >>>> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : >>>> vdev->lock; >>>> + int err; >>>> >>>> - return vb2_mmap(vdev->queue, vma); >>>> + if (lock && mutex_lock_interruptible(lock)) >>>> + return -ERESTARTSYS; >>>> + err = vb2_mmap(vdev->queue, vma); >>>> + if (lock) >>>> + mutex_unlock(lock); >>>> + return err; >>>> } >>>> EXPORT_SYMBOL_GPL(vb2_fop_mmap); >>>> >>>> @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct >>>> file *file, unsigned long addr,>> >>>> unsigned long len, unsigned long pgoff, unsigned long flags) >>>> { >>>> struct video_device *vdev = video_devdata(file); >>>> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : >>>> vdev->lock; >>>> + int ret; >>>> >>>> - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); >>>> + if (lock && mutex_lock_interruptible(lock)) >>>> + return -ERESTARTSYS; >>>> + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); >>>> + if (lock) >>>> + mutex_unlock(lock); >>>> + return ret; >>>> >>>> } >>>> EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area); >>>> #endif > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Hans, On Wednesday 02 July 2014 08:33:47 Hans Verkuil wrote: > For now it is -ENOTIME for me. It's on my TODO list, but there are a number > of other things I want to finish first. No worries, I know how it feels. I just wanted to make sure you hadn't missed my e-mail.
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 9fc4bab..c9b50c7 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf); int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) { struct video_device *vdev = video_devdata(file); + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; + int err; - return vb2_mmap(vdev->queue, vma); + if (lock && mutex_lock_interruptible(lock)) + return -ERESTARTSYS; + err = vb2_mmap(vdev->queue, vma); + if (lock) + mutex_unlock(lock); + return err; } EXPORT_SYMBOL_GPL(vb2_fop_mmap); @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { struct video_device *vdev = video_devdata(file); + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; + int ret; - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); + if (lock && mutex_lock_interruptible(lock)) + return -ERESTARTSYS; + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags); + if (lock) + mutex_unlock(lock); + return ret; } EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area); #endif
The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in implementation of the mmap() and get_unmapped_area() file operations that calls vb2_mmap() and vb2_get_unmapped_area() on the queue associated with the video device. Neither the vb2_fop_mmap/vb2_fop_get_unmapped_area nor the v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any lock, leading to race conditions between mmap/get_unmapped_area and other buffer-related ioctls such as VIDIOC_REQBUFS. Fix it by taking the queue or device lock around the vb2_mmap() and vb2_get_unmapped_area() calls. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> --- drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)