net: ipconfig: ic_dev can be NULL in ic_close_devs
authorVladimir Oltean <vladimir.oltean@nxp.com>
Mon, 22 Mar 2021 00:26:37 +0000 (02:26 +0200)
committerDavid S. Miller <davem@davemloft.net>
Mon, 22 Mar 2021 19:57:51 +0000 (12:57 -0700)
commita50a151e311bd3a793ebe4e5f233db8bfad0b78f
treed81a9fcf75885e0ff423382d1c03be500fe38a8c
parent6debc0fd71b947b03c1a39cc100f52b8238259d4
net: ipconfig: ic_dev can be NULL in ic_close_devs

ic_close_dev contains a generalization of the logic to not close a
network interface if it's the host port for a DSA switch. This logic is
disguised behind an iteration through the lowers of ic_dev in
ic_close_dev.

When no interface for ipconfig can be found, ic_dev is NULL, and
ic_close_dev:
- dereferences a NULL pointer when assigning selected_dev
- would attempt to search through the lower interfaces of a NULL
  net_device pointer

So we should protect against that case.

The "lower_dev" iterator variable was shortened to "lower" in order to
keep the 80 character limit.

Fixes: f68cbaed67cb ("net: ipconfig: avoid use-after-free in ic_close_devs")
Fixes: 46acf7bdbc72 ("Revert "net: ipv4: handle DSA enabled master network devices"")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Heiko Thiery <heiko.thiery@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/ipconfig.c