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From: David Sterba <dsterba@suse.cz>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, ericvh@gmail.com,
	lucho@ionkov.net, viro@zeniv.linux.org.uk, jlayton@kernel.org,
	idryomov@gmail.com, mark@fasheh.com, jlbec@evilplan.org,
	joseph.qi@linux.alibaba.com,
	v9fs-developer@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org,
	ocfs2-devel@oss.oracle.com, linux-btrfs@vger.kernel.org,
	clm@fb.com, josef@toxicpanda.com, dsterba@suse.com,
	stable@vger.kernel.org
Subject: Re: [PATCH 7/7] btrfs: Promote to unsigned long long before multiplying
Date: Mon, 26 Oct 2020 17:21:39 +0100
Message-ID: <20201026162139.GO6756@twin.jikos.cz> (raw)
In-Reply-To: <20201004180428.14494-8-willy@infradead.org>

On Sun, Oct 04, 2020 at 07:04:28PM +0100, Matthew Wilcox (Oracle) wrote:
> On 32-bit systems, these shifts will overflow for files larger than 4GB.
> Add helper functions to avoid this problem coming back.
> 
> Cc: stable@vger.kernel.org
> Fixes: 73ff61dbe5ed ("Btrfs: fix device replace of a missing RAID 5/6 device")
> Fixes: be50a8ddaae1 ("Btrfs: Simplify scrub_setup_recheck_block()'s argument")
> Fixes: ff023aac3119 ("Btrfs: add code to scrub to copy read data to another disk")
> Fixes: b5d67f64f9bc ("Btrfs: change scrub to support big blocks")
> Fixes: a2de733c78fa ("btrfs: scrub")
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  fs/btrfs/scrub.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index 354ab9985a34..ccbaf9c6e87a 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -1262,12 +1262,17 @@ static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
>  	}
>  }
>  
> +static u64 sblock_length(struct scrub_block *sblock)
> +{
> +	return (u64)sblock->page_count * PAGE_SIZE;

page_count will be 32 at most, the type is int and this will never
overflow. The value is usualy number of pages in the arrays scrub_bio::pagev or
scrub_block::pagev bounded by SCRUB_PAGES_PER_WR_BIO (32) or
SCRUB_MAX_PAGES_PER_BLOCK (16).  The scrub code does not use mappings
and it reads raw blocks to own pages and does the checksum verification.

      reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-04 18:04 [PATCH 0/7] Fix a pile of 4GB file problems on 32-bit Matthew Wilcox (Oracle)
2020-10-04 18:04 ` [PATCH 1/7] 9P: Cast to loff_t before multiplying Matthew Wilcox (Oracle)
2020-10-07  5:48   ` Christoph Hellwig
2020-10-07 18:47     ` Matthew Wilcox
2020-10-26 17:14   ` Dominique Martinet
2020-10-04 18:04 ` [PATCH 2/7] buffer: Promote to unsigned long long before shifting Matthew Wilcox (Oracle)
2020-10-04 18:04 ` [PATCH 3/7] ceph: " Matthew Wilcox (Oracle)
2020-10-06 11:29   ` Jeff Layton
2020-10-06 17:20   ` Jeff Layton
2020-10-04 18:04 ` [PATCH 4/7] ocfs2: " Matthew Wilcox (Oracle)
2020-10-04 18:04 ` [PATCH 5/7] btrfs: " Matthew Wilcox (Oracle)
2020-10-09 14:18   ` Josef Bacik
2020-10-26 17:02   ` David Sterba
2020-10-04 18:04 ` [PATCH 6/7] " Matthew Wilcox (Oracle)
2020-10-09 14:18   ` Josef Bacik
2020-10-26 16:35   ` David Sterba
2020-10-26 16:44     ` Matthew Wilcox
2020-10-26 17:03       ` David Sterba
2020-10-04 18:04 ` [PATCH 7/7] btrfs: Promote to unsigned long long before multiplying Matthew Wilcox (Oracle)
2020-10-26 16:21   ` David Sterba [this message]

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