> Add a mutex fixing a potential NULL pointer dereference in the pi433 > driver. > > If pi433_release and pi433_ioctl are concurrently called, > pi433_release might set filp->private_data to NULL while pi433_ioctl > is still accessing it, leading to NULL pointer dereference. This issue > might also affect pi433_write and pi433_read. > > The newly introduced mutex makes sure that instance data > will not be modified simultaneously by pi433_release, pi433_write, > pi433_read or pi433_ioctl. > > The mutex is stored in a newly introduced struct pi433_data, which > wraps struct pi433_instance and its mutex. > > Make filp->private_data point to a struct pi433_data, allowing to > acquire the lock before accessing the struct pi433_instance. > > Signed-off-by: Hugo Lefeuvre <hle@xxxxxxxxxx> > --- > Changes in v2: > - Use mutex instead of rw semaphore. > - Introduce struct pi433_data in order to allow functions to lock > before dereferencing instance pointer. > - Make filp->private_data point to a struct pi433_data. > - Add missing braces. After discussing this issue on the kernel newbies mailing list[0] we came to the conclusion that it is very unlikely that pi433_release and pi433_ioctl would ever run concurrently in this case. This is also true for read/write. Unless one can find a situation where this might happen, I think we should not add this potentially unnecessary lock. Regards, Hugo [0] http://lists.kernelnewbies.org/pipermail/kernelnewbies/2018-June/019131.html -- Hugo Lefeuvre (hle) | www.owl.eu.com 4096/ 9C4F C8BF A4B0 8FC5 48EB 56B8 1962 765B B9A8 BACA _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
