I think a proper fix would be to find the reason why mcryptd crashes and fix that reason (i.e. make it fail in mcryptd_create_hash rather than crash). Testing flags could fix the bug for now but it could backfire later when more algorithms are added. Mikulas On Mon, 5 Dec 2016, Tim Chen wrote: > Algorithms not compatible with mcryptd could be spawned by mcryptd > with a direct crypto_alloc_tfm invocation using a "mcryptd(alg)" name > construct. This causes mcryptd to crash the kernel if an arbitrary > "alg" is incompatible and not intended to be used with mcryptd. It is > an issue if AF_ALG tries to spawn mcryptd(alg) to expose it externally. > But such algorithms must be used internally and not be exposed. > > We added a check to enforce that only internal algorithms are allowed > with mcryptd at the time mcryptd is spawning an algorithm. > > Link: http://marc.info/?l=linux-crypto-vger&m=148063683310477&w=2 > Cc: stable@xxxxxxxxxxxxxxx > Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> > --- > crypto/mcryptd.c | 19 ++++++++++++------- > 1 file changed, 12 insertions(+), 7 deletions(-) > > diff --git a/crypto/mcryptd.c b/crypto/mcryptd.c > index 94ee44a..c207458 100644 > --- a/crypto/mcryptd.c > +++ b/crypto/mcryptd.c > @@ -254,18 +254,22 @@ static void *mcryptd_alloc_instance(struct crypto_alg *alg, unsigned int head, > goto out; > } > > -static inline void mcryptd_check_internal(struct rtattr **tb, u32 *type, > +static inline bool mcryptd_check_internal(struct rtattr **tb, u32 *type, > u32 *mask) > { > struct crypto_attr_type *algt; > > algt = crypto_get_attr_type(tb); > if (IS_ERR(algt)) > - return; > - if ((algt->type & CRYPTO_ALG_INTERNAL)) > - *type |= CRYPTO_ALG_INTERNAL; > - if ((algt->mask & CRYPTO_ALG_INTERNAL)) > - *mask |= CRYPTO_ALG_INTERNAL; > + return false; > + > + *type |= algt->type & CRYPTO_ALG_INTERNAL; > + *mask |= algt->mask & CRYPTO_ALG_INTERNAL; > + > + if (*type & *mask & CRYPTO_ALG_INTERNAL) > + return true; > + else > + return false; > } > > static int mcryptd_hash_init_tfm(struct crypto_tfm *tfm) > @@ -492,7 +496,8 @@ static int mcryptd_create_hash(struct crypto_template *tmpl, struct rtattr **tb, > u32 mask = 0; > int err; > > - mcryptd_check_internal(tb, &type, &mask); > + if (!mcryptd_check_internal(tb, &type, &mask)) > + return -EINVAL; > > halg = ahash_attr_alg(tb[1], type, mask); > if (IS_ERR(halg)) > -- > 2.5.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
