From: Taehee Yoo ap420073@gmail.com

[ Upstream commit a2bed90704c68d3763bf24decb1b781a45395de8 ]

Current gtp_newlink() could be called after unregister_pernet_subsys(). gtp_newlink() uses gtp_net but it can be destroyed by unregister_pernet_subsys(). So unregister_pernet_subsys() should be called after rtnl_link_unregister().

Test commands: #SHELL 1 while : do for i in {1..5} do ./gtp-link add gtp$i & done killall gtp-link done

#SHELL 2 while : do modprobe -rv gtp done

Splat looks like: [ 753.176631] BUG: KASAN: use-after-free in gtp_newlink+0x9b4/0xa5c [gtp] [ 753.177722] Read of size 8 at addr ffff8880d48f2458 by task gtp-link/7126 [ 753.179082] CPU: 0 PID: 7126 Comm: gtp-link Tainted: G W 5.2.0-rc6+ #50 [ 753.185801] Call Trace: [ 753.186264] dump_stack+0x7c/0xbb [ 753.186863] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.187583] print_address_description+0xc7/0x240 [ 753.188382] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.189097] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.189846] __kasan_report+0x12a/0x16f [ 753.190542] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.191298] kasan_report+0xe/0x20 [ 753.191893] gtp_newlink+0x9b4/0xa5c [gtp] [ 753.192580] ? __netlink_ns_capable+0xc3/0xf0 [ 753.193370] __rtnl_newlink+0xb9f/0x11b0 [ ... ] [ 753.241201] Allocated by task 7186: [ 753.241844] save_stack+0x19/0x80 [ 753.242399] __kasan_kmalloc.constprop.3+0xa0/0xd0 [ 753.243192] __kmalloc+0x13e/0x300 [ 753.243764] ops_init+0xd6/0x350 [ 753.244314] register_pernet_operations+0x249/0x6f0 [ ... ] [ 753.251770] Freed by task 7178: [ 753.252288] save_stack+0x19/0x80 [ 753.252833] __kasan_slab_free+0x111/0x150 [ 753.253962] kfree+0xc7/0x280 [ 753.254509] ops_free_list.part.11+0x1c4/0x2d0 [ 753.255241] unregister_pernet_operations+0x262/0x390 [ ... ] [ 753.285883] list_add corruption. next->prev should be prev (ffff8880d48f2458), but was ffff8880d497d878. (next. [ 753.287241] ------------[ cut here ]------------ [ 753.287794] kernel BUG at lib/list_debug.c:25! [ 753.288364] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 753.289099] CPU: 0 PID: 7126 Comm: gtp-link Tainted: G B W 5.2.0-rc6+ #50 [ 753.291036] RIP: 0010:__list_add_valid+0x74/0xd0 [ 753.291589] Code: 48 39 da 75 27 48 39 f5 74 36 48 39 dd 74 31 48 83 c4 08 b8 01 00 00 00 5b 5d c3 48 89 d9 48b [ 753.293779] RSP: 0018:ffff8880cae8f398 EFLAGS: 00010286 [ 753.294401] RAX: 0000000000000075 RBX: ffff8880d497d878 RCX: 0000000000000000 [ 753.296260] RDX: 0000000000000075 RSI: 0000000000000008 RDI: ffffed10195d1e69 [ 753.297070] RBP: ffff8880cd250ae0 R08: ffffed101b4bff21 R09: ffffed101b4bff21 [ 753.297899] R10: 0000000000000001 R11: ffffed101b4bff20 R12: ffff8880d497d878 [ 753.298703] R13: 0000000000000000 R14: ffff8880cd250ae0 R15: ffff8880d48f2458 [ 753.299564] FS: 00007f5f79805740(0000) GS:ffff8880da400000(0000) knlGS:0000000000000000 [ 753.300533] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 753.301231] CR2: 00007fe8c7ef4f10 CR3: 00000000b71a6006 CR4: 00000000000606f0 [ 753.302183] Call Trace: [ 753.302530] gtp_newlink+0x5f6/0xa5c [gtp] [ 753.303037] ? __netlink_ns_capable+0xc3/0xf0 [ 753.303576] __rtnl_newlink+0xb9f/0x11b0 [ 753.304092] ? rtnl_link_unregister+0x230/0x230

Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Signed-off-by: Taehee Yoo ap420073@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/gtp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 60df6e391ad2..7e1df403a37d 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1358,9 +1358,9 @@ late_initcall(gtp_init);

static void __exit gtp_fini(void) { - unregister_pernet_subsys(&gtp_net_ops); genl_unregister_family(&gtp_genl_family); rtnl_link_unregister(&gtp_link_ops); + unregister_pernet_subsys(&gtp_net_ops);

pr_info("GTP module unloaded\n"); }