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| author | Ido Schimmel <idosch@mellanox.com> | 2017-07-12 09:12:53 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-07-12 08:15:52 -0700 |
| commit | 7387dbbcdb2404e189591435527dcc65463819d7 (patch) | |
| tree | 414347ad1ab0e55c58aabeb7e0e43c683728438c /drivers/net | |
| parent | a4e75b76b2ce47e3d964c87689962abb83cc4958 (diff) | |
| download | linux-0-day-7387dbbcdb2404e189591435527dcc65463819d7.tar.gz linux-0-day-7387dbbcdb2404e189591435527dcc65463819d7.tar.xz | |
mlxsw: spectrum_router: Fix use-after-free in route replace
While working on IPv6 route replace I realized we can have a
use-after-free in IPv4 in case the replaced route is offloaded and the
only one using its FIB info.
The problem is that fib_table_insert() drops the reference on the FIB
info of the replaced routes which is eventually freed via call_rcu().
Since the driver doesn't hold a reference on this FIB info it can cause
a use-after-free when it tries to clear the RTNH_F_OFFLOAD flag stored
in fi->fib_flags.
After running the following commands in a loop for enough time with a
KASAN enabled kernel I finally got the below trace.
$ ip route add 192.168.50.0/24 via 192.168.200.1 dev enp3s0np3
$ ip route replace 192.168.50.0/24 dev enp3s0np5
$ ip route del 192.168.50.0/24 dev enp3s0np5
BUG: KASAN: use-after-free in mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
Read of size 4 at addr ffff8803717d9820 by task kworker/u4:2/55
[...]
? mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
? mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
? mlxsw_sp_router_neighs_update_work+0x1cd0/0x1ce0 [mlxsw_spectrum]
? mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
__asan_load4+0x61/0x80
mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
mlxsw_sp_fib_entry_offload_refresh+0xb6/0x370 [mlxsw_spectrum]
mlxsw_sp_router_fib_event_work+0xd1c/0x2780 [mlxsw_spectrum]
[...]
Freed by task 5131:
save_stack_trace+0x16/0x20
save_stack+0x46/0xd0
kasan_slab_free+0x70/0xc0
kfree+0x144/0x570
free_fib_info_rcu+0x2e7/0x410
rcu_process_callbacks+0x4f8/0xe30
__do_softirq+0x1d3/0x9e2
Fix this by taking a reference on the FIB info when creating the nexthop
group it represents and drop it when the group is destroyed.
Fixes: 599cf8f95f22 ("mlxsw: spectrum_router: Add support for route replace")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
| -rw-r--r-- | drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c index 129afc168fd9d..383fef5a8e242 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c @@ -1867,6 +1867,7 @@ mlxsw_sp_nexthop_group_create(struct mlxsw_sp *mlxsw_sp, struct fib_info *fi) nh_grp->gateway = fi->fib_nh->nh_scope == RT_SCOPE_LINK; nh_grp->count = fi->fib_nhs; nh_grp->key.fi = fi; + fib_info_hold(fi); for (i = 0; i < nh_grp->count; i++) { nh = &nh_grp->nexthops[i]; fib_nh = &fi->fib_nh[i]; @@ -1886,6 +1887,7 @@ err_nexthop_init: nh = &nh_grp->nexthops[i]; mlxsw_sp_nexthop_fini(mlxsw_sp, nh); } + fib_info_put(nh_grp->key.fi); kfree(nh_grp); return ERR_PTR(err); } @@ -1904,6 +1906,7 @@ mlxsw_sp_nexthop_group_destroy(struct mlxsw_sp *mlxsw_sp, } mlxsw_sp_nexthop_group_refresh(mlxsw_sp, nh_grp); WARN_ON_ONCE(nh_grp->adj_index_valid); + fib_info_put(nh_grp->key.fi); kfree(nh_grp); } |