On Tue, May 08, 2018 at 03:46:59PM +0200, Hans de Goede wrote: > In vbg_misc_device_ioctl(), the header of the ioctl argument is copied from > the userspace pointer 'arg' and saved to the kernel object 'hdr'. Then the > 'version', 'size_in', and 'size_out' fields of 'hdr' are verified. > > Before this commit, after the checks a buffer for the entire request would > be allocated and then all data including the verified header would be > copied from the userspace 'arg' pointer again. > > Given that the 'arg' pointer resides in userspace, a malicious userspace > process can race to change the data pointed to by 'arg' between the two > copies. By doing so, the user can bypass the verifications on the ioctl > argument. > > This commit fixes this by using the already checked copy of the header > to fill the header part of the allocated buffer and only copying the > remainder of the data from userspace. > > Reported-by: Wenwen Wang <[email protected]> > Signed-off-by: Hans de Goede <[email protected]>
Does this need to go into 4.17-final? Any older kernels? Or can it wait for 4.18-rc1? thanks, greg k-h
