Re: [PATCH v2] erofs/zmap.c: Fix incorrect offset calculation

From: Chao Yu
Date: Mon Jan 09 2023 - 05:42:03 EST


On 2022/12/9 18:21, Siddh Raman Pant wrote:
Effective offset to add to length was being incorrectly calculated,
which resulted in iomap->length being set to 0, triggering a WARN_ON
in iomap_iter_done().

Fix that, and describe it in comments.

This was reported as a crash by syzbot under an issue about a warning
encountered in iomap_iter_done(), but unrelated to erofs.

C reproducer: https://syzkaller.appspot.com/text?tag=ReproC&x=1037a6b2880000
Kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=e2021a61197ebe02
Dashboard link: https://syzkaller.appspot.com/bug?extid=a8e049cd3abd342936b6

Reported-by: syzbot+a8e049cd3abd342936b6@xxxxxxxxxxxxxxxxxxxxxxxxx
Suggested-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
Signed-off-by: Siddh Raman Pant <code@xxxxxxxx>

Reviewed-by: Chao Yu <chao@xxxxxxxxxx>

Thanks,