Re: [PATCH v2] mm/mseal: update VMA end correctly on merge

[David Hildenbrand (Arm)]

On 3/27/26 18:31, Lorenzo Stoakes (Oracle) wrote:
> Previously we stored the end of the current VMA in curr_end, and then upon
> iterating to the next VMA updated curr_start to curr_end to advance to the
> next VMA.
> 
> However, this doesn't take into account the fact that a VMA might be
> updated due to a merge by vma_modify_flags(), which can result in curr_end
> being stale and thus, upon setting curr_start to curr_end, ending up with
> an incorrect curr_start on the next iteration.
> 
> Resolve the issue by setting curr_end to vma->vm_end unconditionally to
> ensure this value remains updated should this occur.
> 
> While we're here, eliminate this entire class of bug by simply setting
> const curr_[start/end] to be clamped to the input range and VMAs, which
> also happens to simplify the logic.
> 
> Reported-by: Antonius <antonius@xxxxxxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-mm/CAK8a0jwWGj9-SgFk0yKFh7i8jMkwKm5b0ao9=kmXWjO54veX2g@xxxxxxxxxxxxxx/
> Suggested-by: David Hildenbrand (ARM) <david@xxxxxxxxxx>
> Acked-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>
> Reviewed-by: Pedro Falcato <pfalcato@xxxxxxx>
> Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@xxxxxxxxxx>
> Fixes: 6c2da14ae1e0 ("mm/mseal: rework mseal apply logic")
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---

Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

-- 
Cheers,

David