[dpdk-stable] patch 'net/iavf: fix uninitialized variable' has been queued to stable release 19.11.4

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 19.11.4

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 07/26/20. 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.

Thanks.

Luca Boccassi

---
>From 8edaa43add38c967cd9b50b8e1cc16329596f445 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/iavf/iavf_ethdev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/iavf/iavf_ethdev.c b/drivers/net/iavf/iavf_ethdev.c
index 266200dbe..3f41eefff 100644
--- a/drivers/net/iavf/iavf_ethdev.c
+++ b/drivers/net/iavf/iavf_ethdev.c
@@ -593,6 +593,8 @@ iavf_dev_link_update(struct rte_eth_dev *dev,
 	struct rte_eth_link new_link;
 	struct iavf_info *vf = IAVF_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.
 	 */
-- 
2.20.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2020-07-24 12:53:52.630171832 +0100
+++ 0106-net-iavf-fix-uninitialized-variable.patch	2020-07-24 12:53:48.359007801 +0100
@@ -1,4 +1,4 @@
-From ca5e39f8535300b247d14865cd8c6b9b4acba38a Mon Sep 17 00:00:00 2001
+From 8edaa43add38c967cd9b50b8e1cc16329596f445 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
@@ -6,6 +6,8 @@
 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)
@@ -48,7 +50,6 @@
 using it.
 
 Fixes: 48de41ca11f0 ("net/avf: enable link status update")
-Cc: stable at dpdk.org
 
 Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
 Acked-by: Qi Zhang <qi.z.zhang at intel.com>
@@ -57,10 +58,10 @@
  1 file changed, 2 insertions(+)
 
 diff --git a/drivers/net/iavf/iavf_ethdev.c b/drivers/net/iavf/iavf_ethdev.c
-index d69e5284e..b0dd49a8d 100644
+index 266200dbe..3f41eefff 100644
 --- a/drivers/net/iavf/iavf_ethdev.c
 +++ b/drivers/net/iavf/iavf_ethdev.c
-@@ -582,6 +582,8 @@ iavf_dev_link_update(struct rte_eth_dev *dev,
+@@ -593,6 +593,8 @@ iavf_dev_link_update(struct rte_eth_dev *dev,
  	struct rte_eth_link new_link;
  	struct iavf_info *vf = IAVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);