From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 22 Jul 2019 14:26:34 +0200
Subject: drbd: dynamically allocate shash descriptor
Git-commit: 77ce56e2bfaa64127ae5e23ef136c0168b818777
Patch-mainline: v5.3-rc2
References: git-fixes

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.

[lduncan: refreshed (fuzz=2) to apply]

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>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/block/drbd/drbd_receiver.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -5284,7 +5284,7 @@ static int drbd_do_auth(struct drbd_conn
 	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;
@@ -5297,6 +5297,13 @@ static int drbd_do_auth(struct drbd_conn
 	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;
 
@@ -5439,7 +5446,10 @@ static int drbd_do_auth(struct drbd_conn
 	kfree(peers_ch);
 	kfree(response);
 	kfree(right_response);
-	shash_desc_zero(desc);
+	if (desc) {
+		shash_desc_zero(desc);
+		kfree(desc);
+	}
 
 	return rv;
 }