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

[syzbot]

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)
 * [new tag]                   ext4_for_linus_bugfixes  -> ext4_for_linus_bugfixes
 * [new tag]                   ext4_for_linus_cleanups  -> ext4_for_linus_cleanups
 * [new tag]                   ext4_for_linus_fixes     -> ext4_for_linus_fixes
 * [new tag]                   ext4_for_linus_fixes2    -> ext4_for_linus_fixes2



Tested on:

commit:         [unknown 
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git e360ba58d067a30a4e3e7d55ebdd919885a058d6
dashboard link: https://syzkaller.appspot.com/bug?extid=345b75652b1d24227443
compiler:       gcc (GCC) 10.1.0-syz 20200507
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1499c287500000