Messages in this thread | | | Date | Tue, 17 Apr 2012 11:22:06 -0700 | Subject | Re: [PATCH c/r -mm] c/r: prctl: Simplify PR_SET_MM on mm::code/data assignment | From | Kees Cook <> |
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On Mon, Apr 16, 2012 at 3:55 PM, Cyrill Gorcunov <gorcunov@openvz.org> wrote: > The mm::start_code, end_code, start_data, end_data members > are set during startup of executable file and are not changed > after. > > But the program itself might map new executable or/and data areas in > time so the original values written into mm fields mentioned above > might not have correspond VMA area at all, thus if one try to > use this prctl codes without underlied VMA, the error will be > returned. > > Drop this requirement. This shrinks the code and eliminates > redundant calls to vma_flags_mismatch. The worst thing one can > do (if say to write some bad values here) -- the weird results > will be shown in /proc/$pid/statm or in /proc/pid/stat. > > Still, assignement of data on stack (such as command line and > environment variables) requires the underlied VMA to exist. > > Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Since this is CAP_SYS_RESOURCE, and mmap_min_addr is CAP_SYS_RAWIO, how about a lower-bounds check against mmap_min_addr? (We're already doing the TASK_SIZE upper check, so this additional sanity checking seems reasonable to me.)
-Kees
-- Kees Cook ChromeOS Security
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