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Subject[PATCH] [v2] drbd: dynamically allocate shash descriptor
Date
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(-)

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
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