crypto: user - fix use_after_free of struct xxx_request

All crypto_stats functions use the struct xxx_request for feeding stats,
but in some case this structure could already be freed.

For fixing this, the needed parameters (len and alg) will be stored
before the request being executed.
Fixes: cac5818c25d0 ("crypto: user - Implement a generic crypto statistics")
Reported-by: syzbot <syzbot+6939a606a5305e9e9799@syzkaller.appspotmail.com>

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 14 insertions, 3 deletions

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 3a348fbcf8f9..5d320a811f75 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -364,20 +364,28 @@ static int crypto_ahash_op(struct ahash_request *req,
 
 int crypto_ahash_final(struct ahash_request *req)
 {
+        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+        struct crypto_alg *alg = tfm->base.__crt_alg;
+        unsigned int nbytes = req->nbytes;
         int ret;
 
+        crypto_stats_get(alg);
         ret = crypto_ahash_op(req, crypto_ahash_reqtfm(req)->final);
-        crypto_stat_ahash_final(req, ret);
+        crypto_stats_ahash_final(nbytes, ret, alg);
         return ret;
 }
 EXPORT_SYMBOL_GPL(crypto_ahash_final);
 
 int crypto_ahash_finup(struct ahash_request *req)
 {
+        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+        struct crypto_alg *alg = tfm->base.__crt_alg;
+        unsigned int nbytes = req->nbytes;
         int ret;
 
+        crypto_stats_get(alg);
         ret = crypto_ahash_op(req, crypto_ahash_reqtfm(req)->finup);
-        crypto_stat_ahash_final(req, ret);
+        crypto_stats_ahash_final(nbytes, ret, alg);
         return ret;
 }
 EXPORT_SYMBOL_GPL(crypto_ahash_finup);
@@ -385,13 +393,16 @@ EXPORT_SYMBOL_GPL(crypto_ahash_finup);
 int crypto_ahash_digest(struct ahash_request *req)
 {
         struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+        struct crypto_alg *alg = tfm->base.__crt_alg;
+        unsigned int nbytes = req->nbytes;
         int ret;
 
+        crypto_stats_get(alg);
         if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
                 ret = -ENOKEY;
         else
                 ret = crypto_ahash_op(req, tfm->digest);
-        crypto_stat_ahash_final(req, ret);
+        crypto_stats_ahash_final(nbytes, ret, alg);
         return ret;
 }
 EXPORT_SYMBOL_GPL(crypto_ahash_digest);