2019-07-22 15:38:32

by Arnd Bergmann

Subject: [PATCH] [v2] 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/[email protected]/
Signed-off-by: Arnd Bergmann <[email protected]>
---
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

2019-07-22 21:16:05

by Kees Cook

Subject: Re: [PATCH] [v2] drbd: dynamically allocate shash descriptor

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/[email protected]/
> Signed-off-by: Arnd Bergmann <[email protected]>

Reviewed-by: Kees Cook <[email protected]>

-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
>

--
Kees Cook

2019-07-23 14:57:51

by Roland Kammerer

Subject: Re: [PATCH] [v2] drbd: dynamically allocate shash descriptor

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/[email protected]/
> Signed-off-by: Arnd Bergmann <[email protected]>

Reviewed-by: Roland Kammerer <[email protected]>

> ---
> 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
>

2019-07-24 02:17:19

by Jens Axboe

Subject: Re: [PATCH] [v2] drbd: dynamically allocate shash descriptor

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.

--
Jens Axboe