net/smc: Fix NULL pointer dereference in smc_pnet_find_ib()

dev_name() was called with dev.parent as argument but without to
NULL-check it before.
Solve this by checking the pointer before the call to dev_name().

Fixes: 191982f0d1e7 ("net/smc: allow PCI IDs as ib device names in the pnet table")
Reported-by: syzbot+03e3e228510223dabd34@syzkaller.appspotmail.com
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
index 7984f88834720c7b26fb350579c55bc6bfc367c6..7055ed10e316271b665abddecc660d3b8ebdf8ad 100644 (file)
--- a/net/smc/smc_pnet.c
+++ b/net/smc/smc_pnet.c
@@ -311,8 +311,9 @@ static struct smc_ib_device *smc_pnet_find_ib(char *ib_name)
        list_for_each_entry(ibdev, &smc_ib_devices.list, list) {
                if (!strncmp(ibdev->ibdev->name, ib_name,
                             sizeof(ibdev->ibdev->name)) ||
-                   !strncmp(dev_name(ibdev->ibdev->dev.parent), ib_name,
-                            IB_DEVICE_NAME_MAX - 1)) {
+                   (ibdev->ibdev->dev.parent &&
+                    !strncmp(dev_name(ibdev->ibdev->dev.parent), ib_name,
+                            IB_DEVICE_NAME_MAX - 1))) {
                        goto out;
                }
        }