Bug#813000: apt complains about corrupted index files even after multiple updates
On Sat, Jan 30, 2016 at 08:42:59PM +0100, Stefan Bühler wrote:
> Hi,
>
> On Sat, 30 Jan 2016 15:03:27 +0100
> Julian Andres Klode <jak@debian.org> wrote:
>
> > On 30 January 2016 at 13:42, Stefan Bühler <stbuehler@web.de> wrote:
> > > [...]
> > > ==890== Conditional jump or move depends on uninitialised value(s)
> > > ==890== at 0x4F4D8A0: pkgCache::ReMap(bool const&)
> > > (in /usr/lib/x86_64-linux-gnu/libapt-pkg.so.5.0.0)> >
> > > [...]
> > > I managed to track down the code (pkgCache::ReMap+0x2d0) in gdbs
> > > disassembly to pkgcache.cc:199:
> > > if (hash != HeaderP->CacheFileSize)
> >
> > That's not an issue, it's expected. We mmap() the memory, and then
> > hash the entire memory we mapped, as that's what we are writing to the
> > disk. It does not matter that there are uninitialized values in there,
> > we just want to check that if we have written it to a file and read it
> > back, that it's the same.
>
> That is sad; I can see now that it should work, but it would be nice if
> this could be fixed one day.
It is.
>
> > > Disabling lz4 seems to fix the issue (but not the valgrind report):
> > >
> > > echo 'APT::Compressor::lz4::Cost "5000";'
> > > > /etc/apt/apt.conf.d/disable-lz4 rm /var/lib/apt/lists/*.lz4
> > > apt-get update
> >
> > OK. Not sure how that happens.
>
> I might add that the docker/debootstrap combo sets (among others) the
> following options by default:
>
> Acquire::GzipIndexes "true";
> Acquire::CompressionTypes::Order:: "gz";
>
> I think in fileutl.cc Lz4FileFdPrivate::InternalOpen() needs to reset
> next_to_load = APT_BUFFER_SIZE, as otherwise a Seek() after reaching
> end of file won't read anything anymore due to next_to_load == 0.
It should be calling close before reopening it again, or as part of
the reopening, I don't remember.
--
Julian Andres Klode - Debian Developer, Ubuntu Member
See http://wiki.debian.org/JulianAndresKlode and http://jak-linux.org/.
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