4.9-stable review patch. If anyone has any objections, please let me know.
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From: Alexey Kodanev alexey.kodanev@oracle.com
[ Upstream commit 4e14bf4236490306004782813b8b4494b18f5e60 ]
The following use-after-free was reported by KASan when running LTP macvtap01 test on 4.16-rc2:
[10642.528443] BUG: KASAN: use-after-free in macvlan_common_newlink+0x12ef/0x14a0 [macvlan] [10642.626607] Read of size 8 at addr ffff880ba49f2100 by task ip/18450 ... [10642.963873] Call Trace: [10642.994352] dump_stack+0x5c/0x7c [10643.035325] print_address_description+0x75/0x290 [10643.092938] kasan_report+0x28d/0x390 [10643.137971] ? macvlan_common_newlink+0x12ef/0x14a0 [macvlan] [10643.207963] macvlan_common_newlink+0x12ef/0x14a0 [macvlan] [10643.275978] macvtap_newlink+0x171/0x260 [macvtap] [10643.334532] rtnl_newlink+0xd4f/0x1300 ... [10646.256176] Allocated by task 18450: [10646.299964] kasan_kmalloc+0xa6/0xd0 [10646.343746] kmem_cache_alloc_trace+0xf1/0x210 [10646.397826] macvlan_common_newlink+0x6de/0x14a0 [macvlan] [10646.464386] macvtap_newlink+0x171/0x260 [macvtap] [10646.522728] rtnl_newlink+0xd4f/0x1300 ... [10647.022028] Freed by task 18450: [10647.061549] __kasan_slab_free+0x138/0x180 [10647.111468] kfree+0x9e/0x1c0 [10647.147869] macvlan_port_destroy+0x3db/0x650 [macvlan] [10647.211411] rollback_registered_many+0x5b9/0xb10 [10647.268715] rollback_registered+0xd9/0x190 [10647.319675] register_netdevice+0x8eb/0xc70 [10647.370635] macvlan_common_newlink+0xe58/0x14a0 [macvlan] [10647.437195] macvtap_newlink+0x171/0x260 [macvtap]
Commit d02fd6e7d293 ("macvlan: Fix one possible double free") handles the case when register_netdevice() invokes ndo_uninit() on error and as a result free the port. But 'macvlan_port_get_rtnl(dev))' check (returns dev->rx_handler_data), which was added by this commit in order to prevent double free, is not quite correct:
* for macvlan it always returns NULL because 'lowerdev' is the one that was used to register rx handler (port) in macvlan_port_create() as well as to unregister it in macvlan_port_destroy(). * for macvtap it always returns a valid pointer because macvtap registers its own rx handler before macvlan_common_newlink().
Fixes: d02fd6e7d293 ("macvlan: Fix one possible double free") Signed-off-by: Alexey Kodanev alexey.kodanev@oracle.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/macvlan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -1384,7 +1384,7 @@ destroy_macvlan_port: /* the macvlan port may be freed by macvlan_uninit when fail to register. * so we destroy the macvlan port only when it's valid. */ - if (create && macvlan_port_get_rtnl(dev)) + if (create && macvlan_port_get_rtnl(lowerdev)) macvlan_port_destroy(port->dev); return err; }