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linux/drivers/net/team
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Nikola Z. Ivanov 4040b5e896 team: Move team device type change at the end of team_port_add 
[ Upstream commit 0ae9cfc454 ]

Attempting to add a port device that is already up will expectedly fail,
but not before modifying the team device header_ops.

In the case of the syzbot reproducer the gre0 device is
already in state UP when it attempts to add it as a
port device of team0, this fails but before that
header_ops->create of team0 is changed from eth_header to ipgre_header
in the call to team_dev_type_check_change.

Later when we end up in ipgre_header() struct ip_tunnel* points to nonsense
as the private data of the device still holds a struct team.

Example sequence of iproute2 commands to reproduce the hang/BUG():
ip link add dev team0 type team
ip link add dev gre0 type gre
ip link set dev gre0 up
ip link set dev gre0 master team0
ip link set dev team0 up
ping -I team0 1.1.1.1

Move team_dev_type_check_change down where all other checks have passed
as it changes the dev type with no way to restore it in case
one of the checks that follow it fail.

Also make sure to preserve the origial mtu assignment:
  - If port_dev is not the same type as dev, dev takes mtu from port_dev
  - If port_dev is the same type as dev, port_dev takes mtu from dev

This is done by adding a conditional before the call to dev_set_mtu
to prevent it from assigning port_dev->mtu = dev->mtu and instead
letting team_dev_type_check_change assign dev->mtu = port_dev->mtu.
The conditional is needed because the patch moves the call to
team_dev_type_check_change past dev_set_mtu.

Testing:
  - team device driver in-tree selftests
  - Add/remove various devices as slaves of team device
  - syzbot

Reported-by: syzbot+a2a3b519de727b0f7903@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=a2a3b519de727b0f7903
Fixes: 1d76efe157 ("team: add support for non-ethernet devices")
Signed-off-by: Nikola Z. Ivanov <zlatistiv@gmail.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/20251122002027.695151-1-zlatistiv@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-12-07 06:24:55 +09:00
..
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile net: team: use policy generated by YAML spec 2024-04-02 18:24:32 -07:00
team_core.c team: Move team device type change at the end of team_port_add 2025-12-07 06:24:55 +09:00
team_mode_activebackup.c team: change the getter function in the team_option structure to void 2023-08-08 15:04:05 -07:00
team_mode_broadcast.c team: remove unreferenced header in broadcast and roundrobin files 2023-08-08 15:04:04 -07:00
team_mode_loadbalance.c team: remove unused input parameters in lb_htpm_select_tx_port and lb_hash_select_tx_port 2023-08-08 15:04:05 -07:00
team_mode_random.c treewide: use get_random_u32_below() instead of deprecated function 2022-11-18 02:15:15 +01:00
team_mode_roundrobin.c team: remove unreferenced header in broadcast and roundrobin files 2023-08-08 15:04:04 -07:00
team_nl.c net: team: use policy generated by YAML spec 2024-04-02 18:24:32 -07:00
team_nl.h net: team: use policy generated by YAML spec 2024-04-02 18:24:32 -07:00