Messages in this thread | | | Date | Wed, 16 Nov 2016 15:49:43 +0100 | From | Peter Zijlstra <> | Subject | Re: perf: fuzzer KASAN unwind_get_return_address |
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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.
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