[dpdk-stable] patch 'net/iavf: fix uninitialized variable' has been queued to LTS release 18.11.10

[Kevin Traynor]

Hi,

FYI, your patch has been queued to LTS release 18.11.10

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 08/25/20. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable-queue

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable-queue/commit/af7961c247910bf9cde1872823626e262d4c9905

Thanks.

Kevin.

---
>From af7961c247910bf9cde1872823626e262d4c9905 Mon Sep 17 00:00:00 2001
From: Ferruh Yigit <ferruh.yigit at intel.com>
Date: Tue, 23 Jun 2020 14:45:31 +0100
Subject: [PATCH] net/iavf: fix uninitialized variable
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

[ upstream commit ca5e39f8535300b247d14865cd8c6b9b4acba38a ]

This is observed with experimental gcc 11, although the older gcc
versions don't complain about it, issue seems a valid one.
gcc version 11.0.0 20200621 (experimental) (GCC)

Build error
.../drivers/net/iavf/iavf_ethdev.c: In function ‘iavf_dev_link_update’:
.../drivers/net/iavf/iavf_ethdev.c:641:6:
    error: ‘new_link’ is used uninitialized [-Werror=uninitialized]
  641 |  if (rte_atomic64_cmpset((uint64_t *)&dev->data->dev_link,
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  642 |     *(uint64_t *)&dev->data->dev_link,
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  643 |     *(uint64_t *)&new_link) == 0)
      |     ~~~~~~~~~~~~~~~~~~~~~~~
.../drivers/net/iavf/iavf_ethdev.c:596:22:
    note: ‘new_link’ declared here
  596 |  struct rte_eth_link new_link;
      |                      ^~~~~~~~
cc1: all warnings being treated as error

All fields of the 'new_link' struct is already set in function, so the
'uninitialized' warning is hard to get. This is because the combination
of aligning and bitfield usage of the struct

The definition of the struct is:
struct rte_eth_link {
        uint32_t link_speed;        /**< ETH_SPEED_NUM_ */
        uint16_t link_duplex  : 1;  /**< ETH_LINK_[HALF/FULL]_DUPLEX */
        uint16_t link_autoneg : 1;  /**< ETH_LINK_[AUTONEG/FIXED] */
        uint16_t link_status  : 1;  /**< ETH_LINK_[DOWN/UP] */
} __rte_aligned(8);      /**< aligned for atomic64 read/write */

Overall the size of the 'struct rte_eth_link' is 64 bits, but function
only sets the 35 bits of it, because only 3 bits of 16 bits variable are
used.
When the struct cast to 'uint64_t' because of the 'rte_atomic64_cmpset'
the upper 29 bits are used without initialization.

To fix the uninitialized usage, memset the variable 'new_link' before
using it.

Fixes: 48de41ca11f0 ("net/avf: enable link status update")

Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
Acked-by: Qi Zhang <qi.z.zhang at intel.com>
---
 drivers/net/avf/avf_ethdev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/avf/avf_ethdev.c b/drivers/net/avf/avf_ethdev.c
index 8000e9c70d..0ab468904c 100644
--- a/drivers/net/avf/avf_ethdev.c
+++ b/drivers/net/avf/avf_ethdev.c
@@ -581,4 +581,6 @@ avf_dev_link_update(struct rte_eth_dev *dev,
 	struct avf_info *vf = AVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);
 
+	memset(&new_link, 0, sizeof(new_link));
+
 	/* Only read status info stored in VF, and the info is updated
 	 *  when receive LINK_CHANGE evnet from PF by Virtchnnl.
-- 
2.26.2

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2020-08-20 16:26:16.339157367 +0100
+++ 0012-net-iavf-fix-uninitialized-variable.patch	2020-08-20 16:26:15.786323979 +0100
@@ -1 +1 @@
-From ca5e39f8535300b247d14865cd8c6b9b4acba38a Mon Sep 17 00:00:00 2001
+From af7961c247910bf9cde1872823626e262d4c9905 Mon Sep 17 00:00:00 2001
@@ -8,0 +9,2 @@
+[ upstream commit ca5e39f8535300b247d14865cd8c6b9b4acba38a ]
+
@@ -51 +52,0 @@
-Cc: stable at dpdk.org
@@ -56 +57 @@
- drivers/net/iavf/iavf_ethdev.c | 2 ++
+ drivers/net/avf/avf_ethdev.c | 2 ++
@@ -59,6 +60,6 @@
-diff --git a/drivers/net/iavf/iavf_ethdev.c b/drivers/net/iavf/iavf_ethdev.c
-index d69e5284ed..b0dd49a8da 100644
---- a/drivers/net/iavf/iavf_ethdev.c
-+++ b/drivers/net/iavf/iavf_ethdev.c
-@@ -583,4 +583,6 @@ iavf_dev_link_update(struct rte_eth_dev *dev,
- 	struct iavf_info *vf = IAVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);
+diff --git a/drivers/net/avf/avf_ethdev.c b/drivers/net/avf/avf_ethdev.c
+index 8000e9c70d..0ab468904c 100644
+--- a/drivers/net/avf/avf_ethdev.c
++++ b/drivers/net/avf/avf_ethdev.c
+@@ -581,4 +581,6 @@ avf_dev_link_update(struct rte_eth_dev *dev,
+ 	struct avf_info *vf = AVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);