Re: [PATCH V2] block: fix .bi_size overflow

[Jens Axboe <axboe@kernel.dk>]

On 7/1/19 8:14 AM, Jens Axboe wrote:
> On 7/1/19 8:05 AM, Jens Axboe wrote:
>> On 7/1/19 1:14 AM, Ming Lei wrote:
>>> 'bio->bi_iter.bi_size' is 'unsigned int', which at most hold 4G - 1
>>> bytes.
>>>
>>> Before 07173c3ec276 ("block: enable multipage bvecs"), one bio can
>>> include very limited pages, and usually at most 256, so the fs bio
>>> size won't be bigger than 1M bytes most of times.
>>>
>>> Since we support multi-page bvec, in theory one fs bio really can
>>> be added > 1M pages, especially in case of hugepage, or big writeback
>>> with too many dirty pages. Then there is chance in which .bi_size
>>> is overflowed.
>>>
>>> Fixes this issue by using bio_full() to check if the added segment may
>>> overflow .bi_size.
>>
>> Any objections to queuing this up for 5.3? It's not a new regression
>> this series.
> 
> I took a closer look, and applied for 5.3 and removed the stable tag.
> We'll need to apply your patch for stable, and I added an adapted
> one for 5.3. I don't want a huge merge hassle because of this.

OK, so we still get conflicts with that, due to both the same page
merge fix, and Christophs 5.3 changes.

I ended up pulling in 5.2-rc6 in for-5.3/block, which resolves at
least most of it, and kept the stable tag since now it's possible
to backport without too much trouble.

-- 
Jens Axboe