lkml.org 
[lkml]   [2018]   [Jun]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH v4 00/17] khwasan: kernel hardware assisted address sanitizer
    On Wed, Jun 27, 2018 at 4:08 PM Andrew Morton <akpm@linux-foundation.org> wrote:
    >
    > On Tue, 26 Jun 2018 15:15:10 +0200 Andrey Konovalov <andreyknvl@google.com> wrote:
    >
    > > This patchset adds a new mode to KASAN [1], which is called KHWASAN
    > > (Kernel HardWare assisted Address SANitizer).
    > >
    > > The plan is to implement HWASan [2] for the kernel with the incentive,
    > > that it's going to have comparable to KASAN performance, but in the same
    > > time consume much less memory, trading that off for somewhat imprecise
    > > bug detection and being supported only for arm64.
    >
    > Why do we consider this to be a worthwhile change?
    >
    > Is KASAN's memory consumption actually a significant problem? Some
    > data regarding that would be very useful.

    On mobile, ASAN's and KASAN's memory usage is a significant problem.
    Not sure if I can find scientific evidence of that.
    CC-ing Vishwath Mohan who deals with KASAN on Android to provide
    anecdotal evidence.

    There are several other benefits too:
    * HWASAN more reliably detects non-linear-buffer-overflows compared to
    ASAN (same for kernel-HWASAN vs kernel-ASAN)
    * Same for detecting use-after-free (since HWASAN doesn't rely on quarantine).
    * Much easier to implement stack-use-after-return detection (which
    IIRC KASAN doesn't have yet, because in KASAN it's too hard)

    > If it is a large problem then we still have that problem on x86, so the
    > problem remains largely unsolved?

    The problem is more significant on mobile devices than on desktop/server.
    I'd love to have [K]HWASAN on x86_64 as well, but it's less trivial since x86_64
    doesn't have an analog of aarch64's top-byte-ignore hardware feature.


    >
    > > ====== Benchmarks
    > >
    > > The following numbers were collected on Odroid C2 board. Both KASAN and
    > > KHWASAN were used in inline instrumentation mode.
    > >
    > > Boot time [1]:
    > > * ~1.7 sec for clean kernel
    > > * ~5.0 sec for KASAN
    > > * ~5.0 sec for KHWASAN
    > >
    > > Slab memory usage after boot [2]:
    > > * ~40 kb for clean kernel
    > > * ~105 kb + 1/8th shadow ~= 118 kb for KASAN
    > > * ~47 kb + 1/16th shadow ~= 50 kb for KHWASAN
    > >
    > > Network performance [3]:
    > > * 8.33 Gbits/sec for clean kernel
    > > * 3.17 Gbits/sec for KASAN
    > > * 2.85 Gbits/sec for KHWASAN
    > >
    > > Note, that KHWASAN (compared to KASAN) doesn't require quarantine.
    > >
    > > [1] Time before the ext4 driver is initialized.
    > > [2] Measured as `cat /proc/meminfo | grep Slab`.
    > > [3] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
    >
    > The above doesn't actually demonstrate the whole point of the
    > patchset: to reduce KASAN's very high memory consumption?
    >
    > --
    > You received this message because you are subscribed to the Google Groups "kasan-dev" group.
    > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com.
    > To post to this group, send email to kasan-dev@googlegroups.com.
    > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20180627160800.3dc7f9ee41c0badbf7342520%40linux-foundation.org.
    > For more options, visit https://groups.google.com/d/optout.

    \
     
     \ /
      Last update: 2018-06-28 02:05    [W:2.838 / U:0.240 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site