lkml.org 
[lkml]   [2011]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] drivers/block/drbd: add NULL test around call to crypto_free_hash


Am 31.01.2011 18:51, schrieb Julia Lawall:
> crypto_free_hash calls the function crypto_hash_tfm and then
> crypto_free_tfm on the result. crypto_free_tfm calls crypto_destroy_tfm,
> which tests this result for NULL and then dereferences it. crypto_hash_tfm
> returns &tfm->base where tfm is its argument. base is actually the first
> and only field of a crypto_hash-typed structure, so perhaps one can rely on
> it to return NULL for a NULL value of tfm. But most calls to
> crypto_hash_tfm where the argument might be NULL don't rely on this
> property and test for NULL explicitly.
>
> The semantic match that finds this problem is as follows:
> (http://coccinelle.lip6.fr/)
>
> // <smpl>
> @safe@
> position p;
> expression x;
> @@
>
> if (x) { <+... crypto_free_hash@p(x) ...+> }
>
> @@
> expression x;
> position p!=safe.p;
> @@
>
> *x = NULL
> ...
> *crypto_free_hash@p(x)
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@diku.dk>
>
> ---
> drivers/block/drbd/drbd_nl.c | 18 ++++++++++++------
> drivers/block/drbd/drbd_receiver.c | 6 ++++--
> 2 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
> index 8cbfaa6..aa5fbc0 100644
> --- a/drivers/block/drbd/drbd_nl.c
> +++ b/drivers/block/drbd/drbd_nl.c
> @@ -1482,13 +1482,16 @@ static int drbd_nl_net_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
> mdev->ee_hash = new_ee_hash;
> }
>
> - crypto_free_hash(mdev->cram_hmac_tfm);
> + if (mdev->cram_hmac_tfm)
> + crypto_free_hash(mdev->cram_hmac_tfm);
> mdev->cram_hmac_tfm = tfm;
>
> - crypto_free_hash(mdev->integrity_w_tfm);
> + if (mdev->integrity_w_tfm)
> + crypto_free_hash(mdev->integrity_w_tfm);
> mdev->integrity_w_tfm = integrity_w_tfm;
>
> - crypto_free_hash(mdev->integrity_r_tfm);
> + if (mdev->integrity_r_tfm)
> + crypto_free_hash(mdev->integrity_r_tfm);
> mdev->integrity_r_tfm = integrity_r_tfm;
>
> kfree(mdev->int_dig_out);
> @@ -1509,9 +1512,12 @@ fail:
> kfree(int_dig_out);
> kfree(int_dig_in);
> kfree(int_dig_vv);
> - crypto_free_hash(tfm);
> - crypto_free_hash(integrity_w_tfm);
> - crypto_free_hash(integrity_r_tfm);
> + if (tfm)
> + crypto_free_hash(tfm);
> + if (integrity_w_tfm)
> + crypto_free_hash(integrity_w_tfm);
> + if (integrity_r_tfm)
> + crypto_free_hash(integrity_r_tfm);
> kfree(new_tl_hash);
> kfree(new_ee_hash);
> kfree(new_conf);
> diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
> index 24487d4..3453cc3 100644
> --- a/drivers/block/drbd/drbd_receiver.c
> +++ b/drivers/block/drbd/drbd_receiver.c
> @@ -2871,9 +2871,11 @@ static int receive_SyncParam(struct drbd_conf *mdev, enum drbd_packets cmd, unsi
> disconnect:
> /* just for completeness: actually not needed,
> * as this is not reached if csums_tfm was ok. */
> - crypto_free_hash(csums_tfm);
> + if (csums_tfm)
> + crypto_free_hash(csums_tfm);
> /* but free the verify_tfm again, if csums_tfm did not work out */
> - crypto_free_hash(verify_tfm);
> + if (verify_tfm)
> + crypto_free_hash(verify_tfm);
> drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
> return FALSE;
> }
>

it looks that it would be more sensibel to change crypto_free_hash() to handle
NULL that would be more consistent with the free() family.

just my 2 cents,
re,
wh




\
 
 \ /
  Last update: 2011-01-31 18:43    [W:1.214 / U:1.000 seconds]
©2003-2014 Jasper Spaans. Advertise on this site