patches for DPDK stable branches
 help / color / mirror / Atom feed
From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Jingjing Wu <jingjing.wu@intel.com>, Beilei Xing <beilei.xing@intel.com>
Cc: dev@dpdk.org, Ferruh Yigit <ferruh.yigit@intel.com>, stable@dpdk.org
Subject: [dpdk-stable] [PATCH] net/iavf: fix uninitialized variable
Date: Tue, 23 Jun 2020 14:45:31 +0100	[thread overview]
Message-ID: <20200623134532.1271737-1-ferruh.yigit@intel.com> (raw)

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.

Cc: stable@dpdk.org

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
---
Reference: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95818
---
 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 2b1066b0a..45c853f19 100644
--- a/drivers/net/iavf/iavf_ethdev.c
+++ b/drivers/net/iavf/iavf_ethdev.c
@@ -596,6 +596,8 @@ 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.
 	 */
-- 
2.25.4


             reply	other threads:[~2020-06-23 13:45 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23 13:45 Ferruh Yigit [this message]
2020-06-30 14:33 ` [dpdk-stable] [dpdk-dev] " Zhang, Qi Z

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200623134532.1271737-1-ferruh.yigit@intel.com \
    --to=ferruh.yigit@intel.com \
    --cc=beilei.xing@intel.com \
    --cc=dev@dpdk.org \
    --cc=jingjing.wu@intel.com \
    --cc=stable@dpdk.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).