[PATCH AUTOSEL 4.14 21/30] drbd: dynamically allocate shash descriptor

[Sasha Levin]

From: Arnd Bergmann <a...@arndb.de>

[ Upstream commit 77ce56e2bfaa64127ae5e23ef136c0168b818777 ]

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-a...@arndb.de/
Reviewed-by: Kees Cook <keesc...@chromium.org>
Reviewed-by: Roland Kammerer <roland.kamme...@linbit.com>
Signed-off-by: Arnd Bergmann <a...@arndb.de>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/block/drbd/drbd_receiver.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/block/drbd/drbd_receiver.c 
b/drivers/block/drbd/drbd_receiver.c
index 1aad373da50e2..8fbdfaacc2226 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -5237,7 +5237,7 @@ 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;
@@ -5250,6 +5250,13 @@ 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;
        desc->flags = 0;
 
@@ -5392,7 +5399,10 @@ 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;
 }
-- 
2.20.1