LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Pavel Skripkin <paskripkin@gmail.com>
To: davem@davemloft.net, kuba@kernel.org, linux@rempel-privat.de,
	himadrispandya@gmail.com, andrew@lunn.ch
Cc: linux-usb@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Pavel Skripkin <paskripkin@gmail.com>,
	syzbot+a631ec9e717fb0423053@syzkaller.appspotmail.com
Subject: [PATCH v2] net: asix: fix uninit value in asix_mdio_read
Date: Sat, 14 Aug 2021 01:42:19 +0300	[thread overview]
Message-ID: <20210813224219.11359-1-paskripkin@gmail.com> (raw)
In-Reply-To: <YRbw1psAc8jQu4ob@lunn.ch>

Syzbot reported uninit-value in asix_mdio_read(). The problem was in
missing error handling. asix_read_cmd() should initialize passed stack
variable smsr, but it can fail in some cases. Then while condidition
checks possibly uninit smsr variable.

Since smsr is uninitialized stack variable, driver can misbehave,
because smsr will be random in case of asix_read_cmd() failure.
Fix it by adding error cheking and just continue the loop instead of
checking uninit value.

Fixes: 8a46f665833a ("net: asix: Avoid looping when the device is disconnected")
Reported-by: syzbot+a631ec9e717fb0423053@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---

Changes in v2:
	1. Fixed previous wrong approach and changed while loop to for loop
	2. Reported-and-tested-by: tag removed, since KMSAN tests can be
	   false positive. Used Reported-by instead.

---
 drivers/net/usb/asix_common.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index ac92bc52a85e..7019c25e591c 100644
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -468,18 +468,25 @@ int asix_mdio_read(struct net_device *netdev, int phy_id, int loc)
 	struct usbnet *dev = netdev_priv(netdev);
 	__le16 res;
 	u8 smsr;
-	int i = 0;
+	int i;
 	int ret;
 
 	mutex_lock(&dev->phy_mutex);
-	do {
+	for (i = 0; i < 30; ++i) {
 		ret = asix_set_sw_mii(dev, 0);
 		if (ret == -ENODEV || ret == -ETIMEDOUT)
 			break;
 		usleep_range(1000, 1100);
 		ret = asix_read_cmd(dev, AX_CMD_STATMNGSTS_REG,
 				    0, 0, 1, &smsr, 0);
-	} while (!(smsr & AX_HOST_EN) && (i++ < 30) && (ret != -ENODEV));
+		if (ret == -ENODEV)
+			break;
+		else if (ret < 0)
+			continue;
+		else if (smsr & AX_HOST_EN)
+			break;
+	}
+
 	if (ret == -ENODEV || ret == -ETIMEDOUT) {
 		mutex_unlock(&dev->phy_mutex);
 		return ret;
-- 
2.32.0


  parent reply	other threads:[~2021-08-13 22:44 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-13 16:01 [PATCH] " Pavel Skripkin
2021-08-13 22:23 ` Andrew Lunn
2021-08-13 22:29   ` Pavel Skripkin
2021-08-13 22:42   ` Pavel Skripkin [this message]
2021-08-13 22:52     ` [PATCH v2] " Jakub Kicinski
2021-08-14 13:55       ` [PATCH v3] net: asix: fix uninit value bugs Pavel Skripkin
2021-08-14 15:36         ` Andrew Lunn
2021-08-14 15:40           ` Pavel Skripkin
2021-08-14 16:20           ` Pavel Skripkin
2021-08-17 16:37           ` [PATCH v4] " Pavel Skripkin
2021-08-18 10:50             ` patchwork-bot+netdevbpf
2021-08-13 22:57     ` [PATCH v2] net: asix: fix uninit value in asix_mdio_read Andrew Lunn

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=20210813224219.11359-1-paskripkin@gmail.com \
    --to=paskripkin@gmail.com \
    --cc=andrew@lunn.ch \
    --cc=davem@davemloft.net \
    --cc=himadrispandya@gmail.com \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=linux@rempel-privat.de \
    --cc=netdev@vger.kernel.org \
    --cc=syzbot+a631ec9e717fb0423053@syzkaller.appspotmail.com \
    --subject='Re: [PATCH v2] net: asix: fix uninit value in asix_mdio_read' \
    /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

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).