Re: [PATCH] erofs: fix interlaced ztailpacking pclusters

[Chao Yu <chao@kernel.org>]

On 8/14/26 14:59, Gao Xiang wrote:
> On-disk sizes of interlaced pclusters should be block-aligned, and
> ztailpacking interlaced pclusters should be invalid at all.
> 
> Currently, mkfs.erofs won't generate any interlaced pcluster with
> ztailpacking enabled, so this doesn't affect any existing valid
> filesystems.
> 
> However, crafted images can contain invalid interlaced ztailpacking
> pclusters, resulting in an out-of-bounds read from a kmap'd page and
> copying irrelevant kernel memory into userspace-visible page cache.

Nitpick, if this can only happen in a fuzz case, we can add unlikely for
!(map->m_flags & EROFS_MAP_META)?

> 
> Reported-by: Haiyang Huang <huanghaiyang83@gmail.com>
> Closes: https://lore.kernel.org/r/20260806065253.1083865-1-huanghaiyang83@gmail.com
> Fixes: fdffc091e6f9 ("erofs: support interlaced uncompressed data for compressed files")
> Signed-off-by: Gao Xiang <xiang@kernel.org>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,