From 8f8abb863fa5a4cc18955c6a0e17af0ded3e4a76 Mon Sep 17 00:00:00 2001
From: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Date: Tue, 10 Oct 2023 00:26:14 +0200
Subject: [PATCH] net: usb: dm9601: fix uninitialized variable use in
dm9601_mdio_read
Git-commit: 8f8abb863fa5a4cc18955c6a0e17af0ded3e4a76
References: git-fixes
Patch-mainline: v6.6-rc6
syzbot has found an uninit-value bug triggered by the dm9601 driver [1].
This error happens because the variable res is not updated if the call
to dm_read_shared_word returns an error. In this particular case -EPROTO
was returned and res stayed uninitialized.
This can be avoided by checking the return value of dm_read_shared_word
and propagating the error if the read operation failed.
[1] https://syzkaller.appspot.com/bug?extid=1f53a30781af65d2c955
Cc: stable@vger.kernel.org
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reported-and-tested-by: syzbot+1f53a30781af65d2c955@syzkaller.appspotmail.com
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Fixes: d0374f4f9c35cdfbee0 ("USB: Davicom DM9601 usbnet driver")
Link: https://lore.kernel.org/r/20231009-topic-dm9601_uninit_mdio_read-v2-1-f2fe39739b6c@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/net/usb/dm9601.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/net/usb/dm9601.c b/drivers/net/usb/dm9601.c
index 48d7d278631e..99ec1d4a972d 100644
--- a/drivers/net/usb/dm9601.c
+++ b/drivers/net/usb/dm9601.c
@@ -222,13 +222,18 @@ static int dm9601_mdio_read(struct net_device *netdev, int phy_id, int loc)
struct usbnet *dev = netdev_priv(netdev);
__le16 res;
+ int err;
if (phy_id) {
netdev_dbg(dev->net, "Only internal phy supported\n");
return 0;
}
- dm_read_shared_word(dev, 1, loc, &res);
+ err = dm_read_shared_word(dev, 1, loc, &res);
+ if (err < 0) {
+ netdev_err(dev->net, "MDIO read error: %d\n", err);
+ return err;
+ }
netdev_dbg(dev->net,
"dm9601_mdio_read() phy_id=0x%02x, loc=0x%02x, returns=0x%04x\n",
--
2.42.0