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? 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. Other than that, suggestions are welcome! thanks, greg k-h
