Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix use-after-free in offloaded map/prog info fill When querying info for an offloaded BPF map or program, bpf_map_offload_info_fill_ns() and bpf_prog_offload_info_fill_ns() obtain the network namespace with get_net(dev_net(offmap->netdev)). However, the associated netdev's netns may be racing with teardown during netns destruction. If the netns refcount has already reached 0, get_net() performs a refcount_t increment on 0, triggering: refcount_t: addition on 0; use-after-free. Although rtnl_lock and bpf_devs_lock ensure the netdev pointer remains valid, they cannot prevent the netns refcount from reaching zero. Fix this by using maybe_get_net() instead of get_net(). maybe_get_net() uses refcount_inc_not_zero() and returns NULL if the refcount is already zero, which causes ns_get_path_cb() to fail and the caller to return -ENOENT -- the correct behavior when the netns is being destroyed.
Affected products
- Linux / Linux4.16 – 4.16
- Linux / Linux0 – 4.16
- Linux / Linux7.1 – *
- Linux / Linux7.0.10 – 7.0.*
- Linux / Linux675fc275a3a2d905535207237402c6d8dcb5fa4b – a51e7fbe94a87e236631a83973d4f558310b2cd2
- Linux / Linux675fc275a3a2d905535207237402c6d8dcb5fa4b – a0c584fc18056709c8e047a82a6045d6c209f4ce