Re: [PATCH 2/2] erofs: validate the extent length for uncompressed pclusters

From: Chao Yu
Date: Tue Dec 06 2022 - 10:14:14 EST


On 2022/12/5 23:00, Gao Xiang wrote:
syzkaller reported a KASAN use-after-free:
https://syzkaller.appspot.com/bug?extid=2ae90e873e97f1faf6f2

The referenced fuzzed image actually has two issues:
- m_pa == 0 as a non-inlined pcluster;
- The logical length is longer than its physical length.

The first issue has already been addressed. This patch addresses
the second issue by checking the extent length validity.

Reported-by: syzbot+2ae90e873e97f1faf6f2@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter")
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>

Reviewed-by: Chao Yu <chao@xxxxxxxxxx>

Thanks,