Re: [bug report] block: integer overflow in __bvec_gap_to_prev()

[Keith Busch]

On Tue, Jun 11, 2024 at 02:23:48PM +0000, Roman Smirnov wrote:
> Hello.
> 
> There is a case of integer overflow in __bvec_gap_to_prev():
> 
> 	((bprv->bv_offset + bprv->bv_len) & lim->virt_boundary_mask);
> 
> bio_vec can cross multiple pages:
> 
> https://lore.kernel.org/lkml/20190215111324.30129-1-ming.lei@xxxxxxxxxx/t/
> 
> So, in case bio has one bio_vec bv_len can have a maximum value of UINT_MAX.
> The check happens in bio_full(). In the case when bv_len is equal to
> UINT_MAX and bv_offset is greater than zero, an overflow may occur.

Does it matter? The lower bits checked against the mask should be the
same regardless of overflow.