Re: UBSAN: shift-out-of-bounds in ext4_fill_super

[Dmitry Vyukov]

On Thu, Dec 10, 2020 at 9:09 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>
> On Thu, Dec 10, 2020 at 4:50 AM syzbot
> <syzbot+345b75652b1d24227443@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Hello,
> >
> > syzbot tried to test the proposed patch but the build/boot failed:
> >
> > failed to checkout kernel repo git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git on commit e360ba58d067a30a4e3e7d55ebdd919885a058d6: failed to run ["git" "fetch" "--tags" "d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8"]: exit status 1
> > From git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
> >  * [new branch]                bisect-test-ext4-035     -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/bisect-test-ext4-035
> >  * [new branch]                bisect-test-generic-307  -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/bisect-test-generic-307
> >  * [new branch]                dev                      -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/dev
> >  * [new branch]                ext4-3.18                -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/ext4-3.18
> >  * [new branch]                ext4-4.1                 -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/ext4-4.1
> >  * [new branch]                ext4-4.4                 -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/ext4-4.4
> >  * [new branch]                ext4-4.9                 -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/ext4-4.9
> >  * [new branch]                ext4-dax                 -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/ext4-dax
> >  * [new branch]                ext4-tools               -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/ext4-tools
> >  * [new branch]                fix-bz-206443            -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/fix-bz-206443
> >  * [new branch]                for-stable               -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/for-stable
> >  * [new branch]                fsverity                 -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/fsverity
> >  * [new branch]                lazy_journal             -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/lazy_journal
> >  * [new branch]                master                   -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/master
> >  * [new branch]                origin                   -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/origin
> >  * [new branch]                pu                       -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/pu
> >  * [new branch]                test                     -> d06f7b29746c7f0a52f349ff7fbf2a3f22d27cf8/test
> >  * [new tag]                   ext4-for-linus-5.8-rc1-2 -> ext4-for-linus-5.8-rc1-2
> >  ! [rejected]                  ext4_for_linus           -> ext4_for_linus  (would clobber existing tag)
>
> Interesting. First time I see this. Should syzkaller use 'git fetch
> --tags --force"?...
> StackOverflow suggests it should help:
> https://stackoverflow.com/questions/58031165/how-to-get-rid-of-would-clobber-existing-tag


I've added --force to fetches:
https://github.com/google/syzkaller/commit/9a72bc3440b65a01187ba4277b49d6bd821079cd
 and it should be deployed by now. Let's try again:

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
e360ba58d067a30a4e3e7d55ebdd919885a058d6

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