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H A D | migrate.c | diff 197e7e521384a23b9e585178f3f11c9fa08274b9 Sun Aug 20 22:26:27 CEST 2017 Linus Torvalds <torvalds@linux-foundation.org> Sanitize 'move_pages()' permission checks
The 'move_paghes()' system call was introduced long long ago with the same permission checks as for sending a signal (except using CAP_SYS_NICE instead of CAP_SYS_KILL for the overriding capability).
That turns out to not be a great choice - while the system call really only moves physical page allocations around (and you need other capabilities to do a lot of it), you can check the return value to map out some the virtual address choices and defeat ASLR of a binary that still shares your uid.
So change the access checks to the more common 'ptrace_may_access()' model instead.
This tightens the access checks for the uid, and also effectively changes the CAP_SYS_NICE check to CAP_SYS_PTRACE, but it's unlikely that anybody really _uses_ this legacy system call any more (we hav ebetter NUMA placement models these days), so I expect nobody to notice.
Famous last words.
Reported-by: Otto Ebeling <otto.ebeling@iki.fi> Acked-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Willy Tarreau <w@1wt.eu> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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