RE: [PATCH rc v2 1/4] iommufd: Fix data_len byte-count vs element-count mismatch

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Friday, May 22, 2026 8:37 AM
> 
> kzalloc_flex() computes the allocation size. With event_data typed as u64,
> data_len is interpreted as a u64 element count. Yet, every caller and the
> read path treat data_len as a byte count. The current code over-allocates
> by sizeof(u64) and the __counted_by() annotation overstates the length by
> the same factor.
> 
> Re-type event_data as u8. No functional change in user-visible behavior.
> 
> Fixes: e36ba5ab808e ("iommufd: Add IOMMUFD_OBJ_VEVENTQ and
> IOMMUFD_CMD_VEVENTQ_ALLOC")
> Cc: stable@xxxxxxxxxxxxxxx
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>