[PATCH] can: j1939: fix double free in j1939_netdev_start

From: trix
Date: Fri Jul 10 2020 - 09:45:55 EST


From: Tom Rix <trix@xxxxxxxxxx>

clang static analysis flags this error

j1939/main.c:292:2: warning: Attempt to free released memory [unix.Malloc]
kfree(priv);
^~~~~~~~~~~

The problem block of code is

ret = j1939_can_rx_register(priv);
if (ret < 0)
goto out_priv_put;

return priv;

out_priv_put:
j1939_priv_set(ndev, NULL);
dev_put(ndev);
kfree(priv);

When j1939_can_rx_register fails, it frees priv via the
j1939_priv_put release function __j1939_priv_release.

Since j1939_priv_put is used widely, remove the second
free from j1939_netdev_start.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")

Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
---
net/can/j1939/main.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
index 137054bff9ec..991a74bc491b 100644
--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c
@@ -289,7 +289,6 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
out_priv_put:
j1939_priv_set(ndev, NULL);
dev_put(ndev);
- kfree(priv);

return ERR_PTR(ret);
}
--
2.18.1