Re: [PATCH] ext4: clear in-inode xattr space before adding the first xattr

[sashiko-bot@kernel.org]

> An inode can hold extended attributes in the space that follows its extra
> fields, whose size is given by i_extra_isize.  When ext4 loads an inode,
> ext4_iget_extra_inode() validates that space only if it starts with the
> xattr magic, and only then sets EXT4_STATE_XATTR.  Without the magic, the
> space is treated as empty and is not checked.
> 
> ext4_xattr_ibody_set() passes the space to ext4_xattr_set_entry() whether
> or not EXT4_STATE_XATTR is set.  ext4_xattr_set_entry() walks the entries
> there to find min_offs, the lowest value offset.  That offset decides
> whether the new value fits and where the value is copied:
> 
> 	free = min_offs - ((void *)last - s->base) - sizeof(__u32);
> 	...
> 	void *val = s->base + min_offs - new_size;
> 
> [ ... ]
> Fixes: ac27a0ec112a ("[PATCH] ext4: initial copy of files from ext3")
> Closes: https://lore.kernel.org/lkml/CANypQFZzxTAH=4QRRDoqH6VAw1daAq88NDWiQKoM7QTOnP40sg@mail.gmail.com/
> Cc: stable@vger.kernel.org
> Assisted-by: Claude Code:claude-opus-5
> Signed-off-by: Jiaming Zhang <r772577952@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260916084723.877552-1-r772577952@gmail.com?part=1