On Wed 17-03-21 14:34:27, Greg KH wrote: > On Wed, Mar 17, 2021 at 01:08:21PM +0100, Michal Hocko wrote: > > Btw. I still have problems with the approach. seq_file is intended to > > provide safe way to dump values to the userspace. Sacrificing > > performance just because of some abuser seems like a wrong way to go as > > Al pointed out earlier. Can we simply stop the abuse and disallow to > > manipulate the buffer directly? I do realize this might be more tricky > > for reasons mentioned in other emails but this is definitely worth > > doing. > > We have to provide a buffer to "write into" somehow, so what is the best > way to stop "abuse" like this? What is wrong about using seq_* interface directly? > Right now, we do have helper functions, sysfs_emit(), that know to stop > the overflow of the buffer size, but porting the whole kernel to them is > going to take a bunch of churn, for almost no real benefit except a > potential random driver that might be doing bad things here that we have > not noticed yet. I am not familiar with sysfs, I just got lost in all the indirection but replacing buffer by the seq_file and operate on that should be possible, no? -- Michal Hocko SUSE Labs
