[Spice-devel] bad id bug in glz decoder

[Frediano Ziglio]

> Hi Ziglio,

> I was wondering if you have had a chance to look at the email below yet.

> Best regards,
> Zhongqiang Huang

Yes, weird, usually git CC people in the commit message, but see 

https://lists.freedesktop.org/archives/spice-devel/2018-April/043230.html 

this was acked and merged. 

Christophe, should we backport to 0.12.8 ? 

Frediano 

> On Mon, Apr 23, 2018 at 5:27 PM, Usepr Xf < useprxf at gmail.com > wrote:

> > I found this code in glz_encoder.c in spice-server:
> 
> > static inline void encode_64(Encoder *encoder, uint64_t word)
> 
> > {
> 
> > encode_32(encoder, (uint32_t)(word >> 32));
> 
> > encode_32(encoder, (uint32_t)(word & 0xffffff));   // <----- is it wrong?
> > 0xffffff should be deleted
> 
> > }
> 

> > On Fri, Apr 13, 2018 at 10:04 PM, Frediano Ziglio < fziglio at redhat.com >
> > wrote:
> 

> > > > Hi all,
> > 
> 

> > > > Sorry to be a bother.
> > 
> 

> > > > After a long time running of glz encode&decode (approx. 4hrs), I came
> > > > across
> > 
> 
> > > > this error.
> > 
> 

> > > > The higher bits (> 24) of the image id is truncated, which makes dist
> > > > less
> > 
> 
> > > > than id . This error seems to happen when the dist across (1<<24)
> > 
> 

> > > Is normal that dist is less then id.
> > 
> 
> > > The id, as far as I know, is incremented from 0 and is a 64 bit, not
> > 
> 
> > > supposed to overflow, is truncated to get the slot and should not be a
> > 
> 
> > > problem. The same check "w->images[slot]-> hdr.id == id - dist" is done
> > > in
> > 
> 
> > > wait_for_image which should return TRUE and so "image && image-> hdr.id
> > > ==
> > > wait->id"
> > 
> 
> > > should be true.
> > 
> 

> > > Could be that g_coroutine_condition_wait returned FALSE? I think that
> > > just
> > > calling
> > 
> 
> > > SPICE_DEBUG is a bug.
> > 
> 

> > > > Can you help me solve this problem?
> > 
> 
> > > > Many thanks.
> > 
> 

> > > > Best regards,
> > 
> 
> > > > Zhongqiang Huang
> > 
> 
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