On Mon, Mar 11, 2019 at 07:13:14PM +0800, Jason Yan wrote: > > > On 2019/3/11 17:41, Daniel Borkmann wrote: > > Hi Jason, > > > > On 03/11/2019 10:18 AM, Jason Yan wrote: > > > Hi, Daniel & Greg > > > > > > This patch (979d63d50c0c bpf: prevent out of bounds speculation on pointer arithmetic) was assigned a CVE (CVE-2019-7308) with a high score: > > > > > > CVSS v3.0 Severity and Metrics: > > > Base Score: 9.8 CRITICAL > > > > > > And this patch is not in stable-4.4, would you please backport this patch to 4.4? > > > > We don't handle kernels as old as 4.4, so someone else would need to > > do the backporting e.g. from your side. The series has been backported > > to the last two most-recent stable kernels at that time (we usually > > follow netdev practice here), and there have been asks about 4.14 as > > well; I've been looking into backporting for the latter last two weeks > > on and off, but there are conflicts all over the place in fragile core > > areas where I didn't have enough free cycles to complete it yet. For > > old kernels, you're probably better off doing something like this in > > your tree instead of the huge complexity with a backport: > > > > Thanks for you kindly reply. > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > index bc34cf9..2cea2de 100644 > > --- a/kernel/bpf/syscall.c > > +++ b/kernel/bpf/syscall.c > > @@ -47,7 +47,7 @@ static DEFINE_SPINLOCK(prog_idr_lock); > > static DEFINE_IDR(map_idr); > > static DEFINE_SPINLOCK(map_idr_lock); > > > > -int sysctl_unprivileged_bpf_disabled __read_mostly; > > +int sysctl_unprivileged_bpf_disabled __read_mostly = 1; > > > > Greg, is it possible to get this kind of mitigation into 4.4? Why are you using a 4.4 kernel with untrusted userspace? The only reason to use 4.4.y at this point in time is if you have a huge SoC tree patchset that is not upstream. If you are using x86, you should be using 4.14.y or newer right now. That being said, no, I am not going to change the default here, that could break people's working setups. I would recommend you just setting this value in your initrd/setup scripts if you want it, that's why it is a sysctl :) thanks, greg k-h
