Re: AUDIT: copy_from_user is a deathtrap.

[Alan Cox]

> So if you pass bad pointer to read(), why would you expect "number of
> bytes read" return? Its true that kernel can't simply not return

Because the standard says either you return the errorcode and no data
is transferred or for a partial I/O you return how much was done. Its
not neccessarily about accuracy either. If you do a 4k copy_from_user and
error after for some reason returning -Esomething thats fine providing you
didnt do anything that consumed data or shifted the file position etc