4.19-stable review patch. If anyone has any objections, please let me know.
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From: Javier Carrasco javier.carrasco.cruz@gmail.com
commit 8f8abb863fa5a4cc18955c6a0e17af0ded3e4a76 upstream.
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-f2fe39... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/usb/dm9601.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/net/usb/dm9601.c +++ b/drivers/net/usb/dm9601.c @@ -221,13 +221,18 @@ static int dm9601_mdio_read(struct net_d 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",