netdev - [PATCH net-next 4/6] ethtool: fec: sanitize ethtool_fecparam->active

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Date:   Wed, 24 Mar 2021 18:11:58 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, ecree.xilinx@...il.com,
        michael.chan@...adcom.com, damian.dybek@...el.com,
        paul.greenwalt@...el.com, rajur@...lsio.com,
        jaroslawx.gawin@...el.com, vkochan@...vell.com, alobakin@...me,
        snelson@...sando.io, shayagr@...zon.com, ayal@...dia.com,
        shenjian15@...wei.com, saeedm@...dia.com, mkubecek@...e.cz,
        andrew@...n.ch, roopa@...dia.com, Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 4/6] ethtool: fec: sanitize ethtool_fecparam->active_fec

struct ethtool_fecparam::active_fec is a GET-only field,
all in-tree drivers correctly ignore it on SET. Clear
the field on SET to avoid any confusion. Again, we can't
reject non-zero now since ethtool user space does not
zero-init the param correctly.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 include/uapi/linux/ethtool.h | 2 +-
 net/ethtool/ioctl.c          | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index 9e2682a67460..517b68c5fcec 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -1374,15 +1374,15 @@ struct ethtool_per_queue_op {
 	__u32	queue_mask[__KERNEL_DIV_ROUND_UP(MAX_NUM_QUEUE, 32)];
 	char	data[];
 };
 
 /**
  * struct ethtool_fecparam - Ethernet forward error correction(fec) parameters
  * @cmd: Command number = %ETHTOOL_GFECPARAM or %ETHTOOL_SFECPARAM
- * @active_fec: FEC mode which is active on the port
+ * @active_fec: FEC mode which is active on the port, GET only.
  * @fec: Bitmask of supported/configured FEC modes
  * @reserved: Reserved for future extensions, ignore on GET, write 0 for SET.
  */
 struct ethtool_fecparam {
 	__u32   cmd;
 	/* bitmask of FEC modes */
 	__u32   active_fec;
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index be3549023d89..237ffe5440ef 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -2582,14 +2582,15 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr)
 
 	if (!dev->ethtool_ops->set_fecparam)
 		return -EOPNOTSUPP;
 
 	if (copy_from_user(&fecparam, useraddr, sizeof(fecparam)))
 		return -EFAULT;
 
+	fecparam.active_fec = 0;
 	fecparam.reserved = 0;
 
 	return dev->ethtool_ops->set_fecparam(dev, &fecparam);
 }
 
 /* The main entry point in this file.  Called from net/core/dev_ioctl.c */
 
-- 
2.30.2