Messages in this thread | | | Date | Tue, 13 Mar 2012 16:23:38 -0400 | From | Dave Jones <> | Subject | Re: tun oops dereferencing garbage nsproxy-> address. |
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On Tue, Mar 13, 2012 at 01:10:06PM -0700, Eric W. Biederman wrote:
> > > > My guess is the fuzzer called some syscall that set current->nsproxy > > > > to garbage (0x0000000100000001), which later got dereferenced when it > > > > subsequently randomly did an open() on tun. > > > > > > It smells like a memory stomp. current->nsproxy is always supposed to > > > have a valid value, and it never would have an odd value. The value > > > should always be at least 8 byte aligned. > > > > > > Since the value is impossible this doesn't feel like a path where the > > > error handling is wrong. > > > > 0x0000000100000001 looks like one of strange values my fuzzer passes syscalls > > when they ask for an address. > > > > So something managed to get that set as nsproxy. The fuzzer avoids calling > > clone(), so are there other syscalls that might set this ? > > setns and unshare might touch the nsproxy for the same reasons as clone, > but the rules are very similar to clone.
Hmm, the only way that seems possible to set nsproxy is if the process was run with CAP_SYS_ADMIN, which it wasn't.
Maybe your theory holds water, and something else wrote that value to the current thread at a random offset. Fun.
Dave
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