linux-kernel - Re: dm crypt: fix memory leak in dm_crypt_integrity_io

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Message-ID: <20190222224518.GA11359@redhat.com>
Date:   Fri, 22 Feb 2019 17:45:18 -0500
From:   Mike Snitzer <snitzer@...hat.com>
To:     sultan@...neltoast.com
Cc:     dm-devel@...hat.com, Alasdair Kergon <agk@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: dm crypt: fix memory leak in dm_crypt_integrity_io_alloc() error
 path

On Sat, Feb 16 2019 at  4:00pm -0500,
sultan@...neltoast.com <sultan@...neltoast.com> wrote:

> From: Sultan Alsawaf <sultan@...neltoast.com>
> 
> dm_crypt_integrity_io_alloc() allocates space for an integrity payload but
> doesn't free it in the error path, leaking memory. Add a bio_integrity_free()
> invocation upon error to fix the memory leak.
> 
> Signed-off-by: Sultan Alsawaf <sultan@...neltoast.com>
> ---
>  drivers/md/dm-crypt.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> index dd538e6b2..f731e1fe0 100644
> --- a/drivers/md/dm-crypt.c
> +++ b/drivers/md/dm-crypt.c
> @@ -939,8 +939,10 @@ static int dm_crypt_integrity_io_alloc(struct dm_crypt_io *io, struct bio *bio)
>  
>  	ret = bio_integrity_add_page(bio, virt_to_page(io->integrity_metadata),
>  				     tag_len, offset_in_page(io->integrity_metadata));
> -	if (unlikely(ret != tag_len))
> +	if (unlikely(ret != tag_len)) {
> +		bio_integrity_free(bio);
>  		return -ENOMEM;
> +	}
>  
>  	return 0;
>  }

Since commit 7c20f11680a4 bio_integrity_free() is no longer and exported
symbol.

But that aside, this dm-crypt clone bio's endio will clean up the bip
once -ENOMEM return starts to make its way out via
crypt_alloc_buffer()'s bio_put().

Mike