Messages in this thread | | | Subject | Re: [PATCH RFC v3] media: em28xx: Fix race condition between open and init function | From | Shuah Khan <> | Date | Thu, 15 Apr 2021 11:25:24 -0600 |
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On 4/15/21 8:07 AM, Igor Matheus Andrade Torrente wrote: > Fixes a race condition - for lack of a more precise term - between > em28xx_v4l2_open and em28xx_v4l2_init, by detaching the v4l2_dev, > media_pad and vdev structs from the em28xx_v4l2, and managing the > lifetime of those objects more dynamicaly. > > The race happens when a thread[1] - containing the em28xx_v4l2_init() > code - calls the v4l2_mc_create_media_graph(), and it return a error, > if a thread[2] - running v4l2_open() - pass the verification point > and reaches the em28xx_v4l2_open() before the thread[1] finishes > the deregistration of v4l2 subsystem, the thread[1] will free all > resources before the em28xx_v4l2_open() can process their things, > because the em28xx_v4l2_init() has the dev->lock. And all this lead > the thread[2] to cause a user-after-free. > > Reported-by: kernel test robot <lkp@intel.com> > Reported-and-tested-by: syzbot+b2391895514ed9ef4a8e@syzkaller.appspotmail.com > Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@gmail.com> > --- > > V2: Add v4l2_i2c_new_subdev null check > Deal with v4l2 subdevs dependencies > > V3: Fix link error when compiled as a module > > --- > drivers/media/usb/em28xx/em28xx-camera.c | 4 +- > drivers/media/usb/em28xx/em28xx-video.c | 300 +++++++++++++++-------- > drivers/media/usb/em28xx/em28xx.h | 6 +- > 3 files changed, 209 insertions(+), 101 deletions(-) >
The changes looks good to me. Have you tried building as a modules and running modprobes and rmmods? You can do that without a device.
thanks, -- Shuah
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