[v2] drbd: dynamically allocate shash descriptor
diff mbox series

Message ID 20190722122647.351002-1-arnd@arndb.de
State New
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Series
  • [v2] drbd: dynamically allocate shash descriptor
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Commit Message

Arnd Bergmann July 22, 2019, 12:26 p.m. UTC
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/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2:
- don't try to zero a NULL descriptor pointer,
  based on review from Roland Kammerer.
---
 drivers/block/drbd/drbd_receiver.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

Comments

Kees Cook July 22, 2019, 4:52 p.m. UTC | #1
On Mon, Jul 22, 2019 at 02:26:34PM +0200, Arnd Bergmann wrote:
> 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/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
> v2:
> - don't try to zero a NULL descriptor pointer,
>   based on review from Roland Kammerer.
> ---
>  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 90ebfcae0ce6..2b3103c30857 100644
> --- 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;
>  }
> -- 
> 2.20.0
>
Roland Kammerer July 23, 2019, 7:47 a.m. UTC | #2
On Mon, Jul 22, 2019 at 02:26:34PM +0200, Arnd Bergmann wrote:
> 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/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Roland Kammerer <roland.kammerer@linbit.com>

> ---
> v2:
> - don't try to zero a NULL descriptor pointer,
>   based on review from Roland Kammerer.
> ---
>  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 90ebfcae0ce6..2b3103c30857 100644
> --- 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;
>  }
> -- 
> 2.20.0
>
Jens Axboe July 23, 2019, 1:35 p.m. UTC | #3
On 7/22/19 6:26 AM, Arnd Bergmann wrote:
> 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.

Applied, thanks.

Patch
diff mbox series

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 90ebfcae0ce6..2b3103c30857 100644
--- 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;
 }