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Groups > linux.kernel > #1443866
| From | Balbir Singh <bsingharora@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2 02/11] mm: Hardened usercopy |
| Date | 2016-07-15 03:50 +0200 |
| Message-ID | <rV0ql-uG-13@gated-at.bofh.it> (permalink) |
| References | <rUAmd-nH-3@gated-at.bofh.it> <rUAmj-nH-27@gated-at.bofh.it> <rUYeS-7FM-5@gated-at.bofh.it> <rUZND-h3-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Jul 14, 2016 at 09:04:18PM -0400, Rik van Riel wrote: > On Fri, 2016-07-15 at 09:20 +1000, Balbir Singh wrote: > > > > == > > > + ((unsigned long)end & (unsigned > > > long)PAGE_MASK))) > > > + return NULL; > > > + > > > + /* Allow if start and end are inside the same compound > > > page. */ > > > + endpage = virt_to_head_page(end); > > > + if (likely(endpage == page)) > > > + return NULL; > > > + > > > + /* Allow special areas, device memory, and sometimes > > > kernel data. */ > > > + if (PageReserved(page) && PageReserved(endpage)) > > > + return NULL; > > > > If we came here, it's likely that endpage > page, do we need to check > > that only the first and last pages are reserved? What about the ones > > in > > the middle? > > I think this will be so rare, we can get away with just > checking the beginning and the end. > But do we want to leave a hole where an aware user space can try a longer copy_* to avoid this check? If it is unlikely should we just bite the bullet and do the check for the entire range? Balbir Singh.
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[PATCH v2 02/11] mm: Hardened usercopy Kees Cook <keescook@chromium.org> - 2016-07-14 00:00 +0200
Re: [PATCH v2 02/11] mm: Hardened usercopy Balbir Singh <bsingharora@gmail.com> - 2016-07-15 01:30 +0200
Re: [PATCH v2 02/11] mm: Hardened usercopy Rik van Riel <riel@redhat.com> - 2016-07-15 03:10 +0200
Re: [PATCH v2 02/11] mm: Hardened usercopy Balbir Singh <bsingharora@gmail.com> - 2016-07-15 03:50 +0200
Re: [PATCH v2 02/11] mm: Hardened usercopy Kees Cook <keescook@chromium.org> - 2016-07-15 06:10 +0200
Re: [PATCH v2 02/11] mm: Hardened usercopy Kees Cook <keescook@chromium.org> - 2016-07-15 07:00 +0200
Re: [PATCH v2 02/11] mm: Hardened usercopy Balbir Singh <bsingharora@gmail.com> - 2016-07-15 15:00 +0200
Re: [PATCH v2 02/11] mm: Hardened usercopy Kees Cook <keescook@chromium.org> - 2016-07-15 06:30 +0200
Re: [kernel-hardening] Re: [PATCH v2 02/11] mm: Hardened usercopy Daniel Micay <danielmicay@gmail.com> - 2016-07-15 21:10 +0200
Re: [kernel-hardening] Re: [PATCH v2 02/11] mm: Hardened usercopy Daniel Micay <danielmicay@gmail.com> - 2016-07-15 21:20 +0200
Re: [kernel-hardening] Re: [PATCH v2 02/11] mm: Hardened usercopy Kees Cook <keescook@chromium.org> - 2016-07-15 21:30 +0200
Re: [kernel-hardening] Re: [PATCH v2 02/11] mm: Hardened usercopy Kees Cook <keescook@chromium.org> - 2016-07-15 21:20 +0200
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