drbd: dynamically allocate shash descriptor

Building with clang and KASAN, we get a warning about an overly large
stack frame on 32-bit architectures:

drivers/block/drbd/drbd_receiver.c:921:31: error: stack frame size of 1280 bytes in function 'conn_connect'
      [-Werror,-Wframe-larger-than=]

We already allocate other data dynamically in this function, so
just do the same for the shash descriptor, which makes up most of
this memory.

Link: https://lore.kernel.org/lkml/20190617132440.2721536-1-arnd@arndb.de/
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Roland Kammerer <roland.kammerer@linbit.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 90ebfcae0ce6e70dafed014f489a4e20e0d8876b..2b3103c308573a5398237bd90d78c6957108ce08 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -5417,7 +5417,7 @@ static int drbd_do_auth(struct drbd_connection *connection)
        unsigned int key_len;
        char secret[SHARED_SECRET_MAX]; /* 64 byte */
        unsigned int resp_size;
-       SHASH_DESC_ON_STACK(desc, connection->cram_hmac_tfm);
+       struct shash_desc *desc;
        struct packet_info pi;
        struct net_conf *nc;
        int err, rv;
@@ -5430,6 +5430,13 @@ static int drbd_do_auth(struct drbd_connection *connection)
        memcpy(secret, nc->shared_secret, key_len);
        rcu_read_unlock();
 
+       desc = kmalloc(sizeof(struct shash_desc) +
+                      crypto_shash_descsize(connection->cram_hmac_tfm),
+                      GFP_KERNEL);
+       if (!desc) {
+               rv = -1;
+               goto fail;
+       }
        desc->tfm = connection->cram_hmac_tfm;
 
        rv = crypto_shash_setkey(connection->cram_hmac_tfm, (u8 *)secret, key_len);
@@ -5571,7 +5578,10 @@ static int drbd_do_auth(struct drbd_connection *connection)
        kfree(peers_ch);
        kfree(response);
        kfree(right_response);
-       shash_desc_zero(desc);
+       if (desc) {
+               shash_desc_zero(desc);
+               kfree(desc);
+       }
 
        return rv;
 }