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@xxxxxxx> --- 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; } -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html