linux-stable/net/dsa
Vladimir Oltean 844f104790 net: dsa: fix netdev_priv() dereference before check on non-DSA netdevice events
After the blamed commit, we started doing this dereference for every
NETDEV_CHANGEUPPER and NETDEV_PRECHANGEUPPER event in the system.

static inline struct dsa_port *dsa_user_to_port(const struct net_device *dev)
{
	struct dsa_user_priv *p = netdev_priv(dev);

	return p->dp;
}

Which is obviously bogus, because not all net_devices have a netdev_priv()
of type struct dsa_user_priv. But struct dsa_user_priv is fairly small,
and p->dp means dereferencing 8 bytes starting with offset 16. Most
drivers allocate that much private memory anyway, making our access not
fault, and we discard the bogus data quickly afterwards, so this wasn't
caught.

But the dummy interface is somewhat special in that it calls
alloc_netdev() with a priv size of 0. So every netdev_priv() dereference
is invalid, and we get this when we emit a NETDEV_PRECHANGEUPPER event
with a VLAN as its new upper:

$ ip link add dummy1 type dummy
$ ip link add link dummy1 name dummy1.100 type vlan id 100
[   43.309174] ==================================================================
[   43.316456] BUG: KASAN: slab-out-of-bounds in dsa_user_prechangeupper+0x30/0xe8
[   43.323835] Read of size 8 at addr ffff3f86481d2990 by task ip/374
[   43.330058]
[   43.342436] Call trace:
[   43.366542]  dsa_user_prechangeupper+0x30/0xe8
[   43.371024]  dsa_user_netdevice_event+0xb38/0xee8
[   43.375768]  notifier_call_chain+0xa4/0x210
[   43.379985]  raw_notifier_call_chain+0x24/0x38
[   43.384464]  __netdev_upper_dev_link+0x3ec/0x5d8
[   43.389120]  netdev_upper_dev_link+0x70/0xa8
[   43.393424]  register_vlan_dev+0x1bc/0x310
[   43.397554]  vlan_newlink+0x210/0x248
[   43.401247]  rtnl_newlink+0x9fc/0xe30
[   43.404942]  rtnetlink_rcv_msg+0x378/0x580

Avoid the kernel oops by dereferencing after the type check, as customary.

Fixes: 4c3f80d22b ("net: dsa: walk through all changeupper notifier functions")
Reported-and-tested-by: syzbot+d81bcd883824180500c8@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/0000000000001d4255060e87545c@google.com/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240110003354.2796778-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-01-11 16:33:52 -08:00
..
Kconfig net: dsa: modularize DSA_TAG_PROTO_NONE 2022-11-22 20:41:45 -08:00
Makefile net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
conduit.c net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
conduit.h net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
devlink.c net: dsa: move rest of devlink setup/teardown to devlink.c 2022-11-22 20:41:47 -08:00
devlink.h net: dsa: move rest of devlink setup/teardown to devlink.c 2022-11-22 20:41:47 -08:00
dsa.c net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
dsa.h net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
netlink.c net: dsa: Rename IFLA_DSA_MASTER to IFLA_DSA_CONDUIT 2023-10-24 13:08:14 -07:00
netlink.h net: dsa: kill off dsa_priv.h 2022-11-22 20:41:54 -08:00
port.c net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
port.h net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
stubs.c net: dsa: replace NETDEV_PRE_CHANGE_HWTSTAMP notifier with a stub 2023-04-09 15:35:49 +01:00
switch.c net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
switch.h net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
tag.c net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
tag.h net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
tag_8021q.c net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
tag_8021q.h net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00
tag_ar9331.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_brcm.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_dsa.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_gswip.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_hellcreek.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_ksz.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_lan9303.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_mtk.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_none.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_ocelot.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_ocelot_8021q.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_qca.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_rtl4_a.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_rtl8_4.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_rzn1_a5psw.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_sja1105.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_trailer.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
tag_xrs700x.c net: fill in MODULE_DESCRIPTION()s for DSA tags 2024-01-05 08:06:19 -08:00
trace.c net: dsa: add trace points for FDB/MDB operations 2023-04-12 08:36:07 +01:00
trace.h net: dsa: add trace points for VLAN operations 2023-04-12 08:36:07 +01:00
user.c net: dsa: fix netdev_priv() dereference before check on non-DSA netdevice events 2024-01-11 16:33:52 -08:00
user.h net: dsa: Use conduit and user terms 2023-10-24 13:08:14 -07:00