On 3/24/19 12:48 AM, Xin Long wrote:
> When running a syz script, a panic occurred:
>
> [ 156.088228] BUG: KASAN: use-after-free in tipc_disc_timeout+0x9c9/0xb20
> [tipc]
> [ 156.094315] Call Trace:
> [ 156.094844] <IRQ>
> [ 156.095306] dump_stack+0x7c/0xc0
> [ 156.097346] print_address_description+0x65/0x22e
> [ 156.100445] kasan_report.cold.3+0x37/0x7a
> [ 156.102402] tipc_disc_timeout+0x9c9/0xb20 [tipc]
> [ 156.106517] call_timer_fn+0x19a/0x610
> [ 156.112749] run_timer_softirq+0xb51/0x1090
>
> It was caused by the netns freed without deleting the discoverer timer,
> while later on the netns would be accessed in the timer handler.
>
> The timer should have been deleted by tipc_net_stop() when cleaning up a
> netns. However, tipc has been able to enable a bearer and start d->timer
> without the local node_addr set since Commit 52dfae5c85a4 ("tipc: obtain
> node identity from interface by default"), which caused the timer not to
> be deleted in tipc_net_stop() then.
>
> So fix it in tipc_net_stop() by changing to check local node_id instead
> of local node_addr, as Jon suggested.
>
> While at it, remove the calling of tipc_nametbl_withdraw() there, since
> tipc_nametbl_stop() will take of the nametbl's freeing after.
>
> Fixes: 52dfae5c85a4 ("tipc: obtain node identity from interface by default")
> Reported-by: [email protected]
> Signed-off-by: Xin Long <[email protected]>
Acked-by: Ying Xue <[email protected]>
> ---
> net/tipc/net.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/net/tipc/net.c b/net/tipc/net.c
> index f076edb..7ce1e86 100644
> --- a/net/tipc/net.c
> +++ b/net/tipc/net.c
> @@ -163,12 +163,9 @@ void tipc_sched_net_finalize(struct net *net, u32 addr)
>
> void tipc_net_stop(struct net *net)
> {
> - u32 self = tipc_own_addr(net);
> -
> - if (!self)
> + if (!tipc_own_id(net))
> return;
>
> - tipc_nametbl_withdraw(net, TIPC_CFG_SRV, self, self, self);
> rtnl_lock();
> tipc_bearer_stop(net);
> tipc_node_stop(net);
>
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