lkml.org 
[lkml]   [2016]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: perf: fuzzer KASAN unwind_get_return_address
    On Wed, Nov 16, 2016 at 08:37:46AM -0600, Josh Poimboeuf wrote:
    > On Wed, Nov 16, 2016 at 02:03:37PM +0100, Peter Zijlstra wrote:
    > > On Tue, Nov 15, 2016 at 02:57:48PM -0600, Josh Poimboeuf wrote:
    > > > Would you mind posting a disassembly of unwind_get_return_address()?
    > > > Any idea how recreatable it is? (In particular I'd be interested in
    > > > seeing this dump with the latest unwinder improvements in the -tip tree,
    > > > which dump the pt_regs associated with an interrupt.)
    > >
    > > Fairly reproducable it seems, doesn't seem to include pt_regs dumps
    > > though :/
    > >
    > > tip/master as of this morning.
    >
    > Thanks. This is actually a different issue than the one reported by
    > Vince. In this case FRAME_POINTER is disabled, so it uses the "guess"
    > unwinder which scans every address on the stack, looking for text
    > addresses. So the kasan errors are expected.
    >
    > (The missing pt_regs are also expected: the guess unwinder doesn't show
    > them.)
    >
    > I'll work up a patch to fix this. I still have no idea what's causing
    > Vince's bug in the frame pointer unwinder.

    Hurm,.. by the number of '?' entries in Vince's backtrace I was assuming
    it was without frame pointers.

    Let me enable those and run again, it didn't insta-trigger like it does
    without.

    \
     
     \ /
      Last update: 2016-11-16 15:50    [W:9.023 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site