ubifs: fix wrong use of crypto_shash_descsize()

crypto_shash_descsize() returns the size of the shash_desc context
needed to compute the hash, not the size of the hash itself.

crypto_shash_digestsize() would be correct, or alternatively using
c->hash_len and c->hmac_desc_len which already store the correct values.
But actually it's simpler to just use stack arrays, so do that instead.

Fixes: 49525e5eecca ("ubifs: Add helper functions for authentication support")
Fixes: da8ef65f9573 ("ubifs: Authenticate replayed journal")
Cc: <stable@vger.kernel.org> # v4.20+
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c
index 8cdbd53..f985a3f 100644 (file)
--- a/fs/ubifs/auth.c
+++ b/fs/ubifs/auth.c
@@ -79,13 +79,9 @@ int ubifs_prepare_auth_node(struct ubifs_info *c, void *node,
                             struct shash_desc *inhash)
 {
        struct ubifs_auth_node *auth = node;
-       u8 *hash;
+       u8 hash[UBIFS_HASH_ARR_SZ];
        int err;
 
-       hash = kmalloc(crypto_shash_descsize(c->hash_tfm), GFP_NOFS);
-       if (!hash)
-               return -ENOMEM;
-
        {
                SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm);
 
@@ -94,21 +90,16 @@ int ubifs_prepare_auth_node(struct ubifs_info *c, void *node,
 
                err = crypto_shash_final(hash_desc, hash);
                if (err)
-                       goto out;
+                       return err;
        }
 
        err = ubifs_hash_calc_hmac(c, hash, auth->hmac);
        if (err)
-               goto out;
+               return err;
 
        auth->ch.node_type = UBIFS_AUTH_NODE;
        ubifs_prepare_node(c, auth, ubifs_auth_node_sz(c), 0);
-
-       err = 0;
-out:
-       kfree(hash);
-
-       return err;
+       return 0;
 }
 
 static struct shash_desc *ubifs_get_desc(const struct ubifs_info *c,

diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index b28ac4d..01fcf79 100644 (file)
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -601,18 +601,12 @@ static int authenticate_sleb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
        struct ubifs_scan_node *snod;
        int n_nodes = 0;
        int err;
-       u8 *hash, *hmac;
+       u8 hash[UBIFS_HASH_ARR_SZ];
+       u8 hmac[UBIFS_HMAC_ARR_SZ];
 
        if (!ubifs_authenticated(c))
                return sleb->nodes_cnt;
 
-       hash = kmalloc(crypto_shash_descsize(c->hash_tfm), GFP_NOFS);
-       hmac = kmalloc(c->hmac_desc_len, GFP_NOFS);
-       if (!hash || !hmac) {
-               err = -ENOMEM;
-               goto out;
-       }
-
        list_for_each_entry(snod, &sleb->nodes, list) {
 
                n_nodes++;
@@ -662,9 +656,6 @@ static int authenticate_sleb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
                err = 0;
        }
 out:
-       kfree(hash);
-       kfree(hmac);
-
        return err ? err : n_nodes - n_not_auth;
 }