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authorEric Biggers <ebiggers@google.com>2019-07-03 00:17:00 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2019-07-03 17:11:55 +0300
commit21d4120ec6f5b5992b01b96ac484701163917b63 (patch)
tree18d69b23e94f70441f7399bbb9a3dd8b303d6d51
parent1a0fad630e0b7cff38e7691b28b0517cfbb0633f (diff)
downloadlinux-21d4120ec6f5b5992b01b96ac484701163917b63.tar.xz
crypto: user - prevent operating on larval algorithms
Michal Suchanek reported [1] that running the pcrypt_aead01 test from LTP [2] in a loop and holding Ctrl-C causes a NULL dereference of alg->cra_users.next in crypto_remove_spawns(), via crypto_del_alg(). The test repeatedly uses CRYPTO_MSG_NEWALG and CRYPTO_MSG_DELALG. The crash occurs when the instance that CRYPTO_MSG_DELALG is trying to unregister isn't a real registered algorithm, but rather is a "test larval", which is a special "algorithm" added to the algorithms list while the real algorithm is still being tested. Larvals don't have initialized cra_users, so that causes the crash. Normally pcrypt_aead01 doesn't trigger this because CRYPTO_MSG_NEWALG waits for the algorithm to be tested; however, CRYPTO_MSG_NEWALG returns early when interrupted. Everything else in the "crypto user configuration" API has this same bug too, i.e. it inappropriately allows operating on larval algorithms (though it doesn't look like the other cases can cause a crash). Fix this by making crypto_alg_match() exclude larval algorithms. [1] https://lkml.kernel.org/r/20190625071624.27039-1-msuchanek@suse.de [2] https://github.com/linux-test-project/ltp/blob/20190517/testcases/kernel/crypto/pcrypt_aead01.c Reported-by: Michal Suchanek <msuchanek@suse.de> Fixes: a38f7907b926 ("crypto: Add userspace configuration API") Cc: <stable@vger.kernel.org> # v3.2+ Cc: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
-rw-r--r--crypto/crypto_user_base.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/crypto/crypto_user_base.c b/crypto/crypto_user_base.c
index f25d3f32c9c2..f93b691f8045 100644
--- a/crypto/crypto_user_base.c
+++ b/crypto/crypto_user_base.c
@@ -56,6 +56,9 @@ struct crypto_alg *crypto_alg_match(struct crypto_user_alg *p, int exact)
list_for_each_entry(q, &crypto_alg_list, cra_list) {
int match = 0;
+ if (crypto_is_larval(q))
+ continue;
+
if ((q->cra_flags ^ p->cru_type) & p->cru_mask)
continue;