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    Subject[PATCH AUTOSEL 4.9 15/22] drbd: dynamically allocate shash descriptor
    Date
    From: Arnd Bergmann <arnd@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-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>
    Signed-off-by: Sasha Levin <sashal@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 83957a1e15ed7..8e8e4ccb128f3 100644
    --- a/drivers/block/drbd/drbd_receiver.c
    +++ b/drivers/block/drbd/drbd_receiver.c
    @@ -5297,7 +5297,7 @@ 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;
    @@ -5310,6 +5310,13 @@ 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;

    @@ -5452,7 +5459,10 @@ 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
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