Messages in this thread | | | Subject | Re: [PATCH v1 1/6] fs/readdir: Fix filldir() and filldir64() use of user_access_begin() | From | Christophe Leroy <> | Date | Wed, 22 Jan 2020 18:54:45 +0100 |
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Le 22/01/2020 à 18:41, Al Viro a écrit : > On Wed, Jan 22, 2020 at 08:13:12AM -0800, Linus Torvalds wrote: >> On Wed, Jan 22, 2020 at 5:00 AM Christophe Leroy >> <christophe.leroy@c-s.fr> wrote: >>> >>> Modify filldir() and filldir64() to request the real area they need >>> to get access to. >> >> Not like this. >> >> This makes the situation for architectures like x86 much worse, since >> you now use "put_user()" for the previous dirent filling. Which does >> that expensive user access setup/teardown twice again. >> >> So either you need to cover both the dirent's with one call, or you >> just need to cover the whole (original) user buffer passed in. But not >> this unholy mixing of both unsafe_put_user() and regular put_user(). > > I would suggest simply covering the range from dirent->d_off to > buf->current_dir->d_name[namelen]; they are going to be close to > each other and we need those addresses anyway... >
In v2, I'm covering from the beginning of parent dirent to the end of current dirent.
Christophe
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