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version 1.79, 1998/02/19 22:03:22

version 1.80, 1998/02/21 00:42:37

Line 65

<li>SECURITY FIX

If you rely on the system securelevels as described in init(8), you

A bug in the vm system permits a file descriptor opened read-only on a

will want this fix. A bug in the vm system permits a file descriptor

device, to later on be mmap(2)'d read-write, and then modified. This

opened read-only on a device, to later on be mmap(2)'d read-write, and

does not result in a security hole by itself, but it does violate the

then modified. This does not result in a security hole by itself, but

safety semantics which securelevels are supposed to provide. If a user

it does violate the safety semantics which securelevels are supposed to

manages to gain kmem group permissions, using this problem they can then

provide. If a user manages to gain kmem group permissions, using this

gain root trivially and/or turn securelevels off.

problem they can then gain root trivially.

A kernel patch is available which corrects this behaviour (this is

revision 2 of this patch)</a>.