[PATCH v3] erofs: validate h_shared_count in erofs_init_inode_xattrs()

[Gao Xiang]

On Tue, Mar 17, 2026 at 04:41:35PM +0000, Utkal Singh wrote:
> A crafted image can set h_shared_count to a value much larger than
> what xattr_isize allows. The loop in erofs_init_inode_xattrs() then
> reads shared xattr IDs far beyond the inode's xattr region, causing
> an out-of-bounds metadata read.
> 
> Add a sanity check ensuring:
> 
>   h_shared_count <= (xattr_isize - sizeof(erofs_xattr_ibody_header)) / 4
> 
> Return -EFSCORRUPTED when the check fails.
> 
> Signed-off-by: Utkal Singh <singhutkal015 at gmail.com>

What happens with your v3?

What happens with the commit message and the division?

Could you explain what happened?

Thanks,
Gao Xiang