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    SubjectRe: [Patch 2.6] dm-crypt: zero key before freeing it

    >
    >Hi Andrew,
    >
    >dm-crypt does not clear struct crypt_config before freeing it. Thus,
    >information on the key could leak f.e. to a swsusp image even after the
    >encrypted device has been removed. The attached patch against 2.6.14 / 2.6.15
    >fixes it.
    >
    >Signed-off-by: Stefan Rompf <stefan@loplof.de>
    >Acked-by: Clemens Fruhwirth <clemens@endorphin.org>
    >
    >--- linux-2.6.14.4/drivers/md/dm-crypt.c.old 2005-12-16 18:27:05.000000000 +0100
    >+++ linux-2.6.14.4/drivers/md/dm-crypt.c 2005-12-28 12:49:13.000000000 +0100
    >@@ -694,6 +694,7 @@ bad3:
    > bad2:
    > crypto_free_tfm(tfm);
    > bad1:
    >+ memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
    > kfree(cc);
    > return -EINVAL;
    > }

    There is a small problem with this patch.
    If the 'goto bad1' branch is taken, then 'cc->key_size' will not be
    defined.
    I think you need the following patch on top.

    (Is that "sizeof(u8)" *really* necessary?? :-)

    NeilBrown


    Signed-off-by: Neil Brown <neilb@suse.de>

    ### Diffstat output
    ./drivers/md/dm-crypt.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff ./drivers/md/dm-crypt.c~current~ ./drivers/md/dm-crypt.c
    --- ./drivers/md/dm-crypt.c~current~ 2006-01-24 15:42:52.000000000 +1100
    +++ ./drivers/md/dm-crypt.c 2006-01-24 15:43:07.000000000 +1100
    @@ -691,7 +691,7 @@ bad2:
    crypto_free_tfm(tfm);
    bad1:
    /* Must zero key material before freeing */
    - memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
    + memset(cc, 0, sizeof(*cc) + key_size * sizeof(u8));
    kfree(cc);
    return -EINVAL;
    }
    -
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