On 06.11.2019 22:43, Christos Zoulas wrote: > In article <20191106130732.c6c5af...@cvs.netbsd.org>, > Kamil Rytarowski <source-changes-d@NetBSD.org> wrote: >> -=-=-=-=-=- >> >> Module Name: src >> Committed By: kamil >> Date: Wed Nov 6 13:07:32 UTC 2019 >> >> Modified Files: >> src/sys/kern: subr_disk_mbr.c >> >> Log Message: >> Avoid unaligned pointer arithmetic in check_label_magic() >> >> Replace the logic of calculating the address with with base + offset. >> >> Reported by GCC8. >> >> Reported-by: >> syzbot+56769dece0ec3e357...@syzkaller.appspotmail.com > > I consider this a false positive and the new code less readable. This looks > more like "appease the sanitizer"... > > christos >
Technically, I think that this is a real UB. 6.3.2.3/7 A pointer to an object type may be converted to a pointer to a different object type. If the resulting pointer is not correctly aligned for the referenced type, the behavior is undefined. I agree that this is appeasing the sanitizer.
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