Messages in this thread | | | Subject | Re: [Patch 5 of 8] Add the __stack_chk_fail() function | From | Nix <> | Date | Sun, 19 Mar 2006 19:06:48 +0000 |
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On Sun, 19 Mar 2006, Arjan van de Ven yowled: > Nix wrote: >> On 17 Mar 2006, Arjan van de Ven wrote: >>> GCC emits a call to a __stack_chk_fail() function when the cookie is not matching the expected value. Since this is a bad >>> security issue; lets panic >>> the kernel >> This turns even minor buffer overflows into complete denials of service. > > only those who otherwise would get to the return address. So it turns a "own the machine" into a panic. > Not a "no side effects" thing....
True. Also...
> maybe. The big question is if you can still trust the machine. That is highly questionable... > (and to kill the process you again need to trust bits of the stack, to get to current for example; > and you just found that the stack was compromised)
... that's true, and furthermore it allows the attack vector of `compromise global state, then allow this process to die and allow the global compromise to take over the box'.
Possibly for UML images you can core dump the entire UML for later analysis. Can't do that with Xen, though, unless we can be sure that a compromised guest can't affect any other guests or the hypervisor (which we know to be untrue in the case of at least *one[ guest).
-- `Come now, you should know that whenever you plan the duration of your unplanned downtime, you should add in padding for random management freakouts.' - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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