From: "Lukáš Czerner" <lczerner@redhat.com>
To: Jan Kara <jack@suse.cz>
Cc: Ted Tso <tytso@mit.edu>,
linux-ext4@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] ext4: Fix overflow when updating superblock backups after resize
Date: Wed, 22 Oct 2014 17:00:47 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.00.1410221700200.2250@localhost.localdomain> (raw)
In-Reply-To: <1413988148-11433-1-git-send-email-jack@suse.cz>
On Wed, 22 Oct 2014, Jan Kara wrote:
> Date: Wed, 22 Oct 2014 16:29:08 +0200
> From: Jan Kara <jack@suse.cz>
> To: Ted Tso <tytso@mit.edu>
> Cc: linux-ext4@vger.kernel.org, Jan Kara <jack@suse.cz>,
> stable@vger.kernel.org
> Subject: [PATCH] ext4: Fix overflow when updating superblock backups after
> resize
>
> When there are no meta block groups update_backups() will compute the
> backup block in 32-bit arithmetics thus possibly overflowing the block
> number and corrupting the filesystem. OTOH filesystems without meta
> block groups larger than 16 TB should be rare. Fix the problem by doing
> the counting in 64-bit arithmetics.
Looks good, thanks.
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
>
> Coverity-id: 741252
> CC: stable@vger.kernel.org
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
> fs/ext4/resize.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index f298c60f907d..ca4588388fc3 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -1081,7 +1081,7 @@ static void update_backups(struct super_block *sb, int blk_off, char *data,
> break;
>
> if (meta_bg == 0)
> - backup_block = group * bpg + blk_off;
> + backup_block = ((ext4_fsblk_t)group) * bpg + blk_off;
> else
> backup_block = (ext4_group_first_block_no(sb, group) +
> ext4_bg_has_super(sb, group));
>
next prev parent reply other threads:[~2014-10-22 15:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 14:29 [PATCH] ext4: Fix overflow when updating superblock backups after resize Jan Kara
2014-10-22 15:00 ` Lukáš Czerner [this message]
2014-10-28 20:40 ` Theodore Ts'o
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