osmocom-net-gprs

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[PATCH AUTOSEL 5.2 245/249] gtp: fix Illegal context switch in RCU read-side critical section.
by Sasha Levin 15 Jul '19

15 Jul '19

From: Taehee Yoo <ap420073(a)gmail.com> [ Upstream commit 3f167e1921865b379a9becf03828e7202c7b4917 ] ipv4_pdp_add() is called in RCU read-side critical section. So GFP_KERNEL should not be used in the function. This patch make ipv4_pdp_add() to use GFP_ATOMIC instead of GFP_KERNEL. Test commands: gtp-link add gtp1 & gtp-tunnel add gtp1 v1 100 200 1.1.1.1 2.2.2.2 Splat looks like: [ 130.618881] ============================= [ 130.626382] WARNING: suspicious RCU usage [ 130.626994] 5.2.0-rc6+ #50 Not tainted [ 130.627622] ----------------------------- [ 130.628223] ./include/linux/rcupdate.h:266 Illegal context switch in RCU read-side critical section! [ 130.629684] [ 130.629684] other info that might help us debug this: [ 130.629684] [ 130.631022] [ 130.631022] rcu_scheduler_active = 2, debug_locks = 1 [ 130.632136] 4 locks held by gtp-tunnel/1025: [ 130.632925] #0: 000000002b93c8b7 (cb_lock){++++}, at: genl_rcv+0x15/0x40 [ 130.634159] #1: 00000000f17bc999 (genl_mutex){+.+.}, at: genl_rcv_msg+0xfb/0x130 [ 130.635487] #2: 00000000c644ed8e (rtnl_mutex){+.+.}, at: gtp_genl_new_pdp+0x18c/0x1150 [gtp] [ 130.636936] #3: 0000000007a1cde7 (rcu_read_lock){....}, at: gtp_genl_new_pdp+0x187/0x1150 [gtp] [ 130.638348] [ 130.638348] stack backtrace: [ 130.639062] CPU: 1 PID: 1025 Comm: gtp-tunnel Not tainted 5.2.0-rc6+ #50 [ 130.641318] Call Trace: [ 130.641707] dump_stack+0x7c/0xbb [ 130.642252] ___might_sleep+0x2c0/0x3b0 [ 130.642862] kmem_cache_alloc_trace+0x1cd/0x2b0 [ 130.643591] gtp_genl_new_pdp+0x6c5/0x1150 [gtp] [ 130.644371] genl_family_rcv_msg+0x63a/0x1030 [ 130.645074] ? mutex_lock_io_nested+0x1090/0x1090 [ 130.645845] ? genl_unregister_family+0x630/0x630 [ 130.646592] ? debug_show_all_locks+0x2d0/0x2d0 [ 130.647293] ? check_flags.part.40+0x440/0x440 [ 130.648099] genl_rcv_msg+0xa3/0x130 [ ... ] Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> Signed-off-by: David S. Miller <davem(a)davemloft.net> Signed-off-by: Sasha Levin <sashal(a)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 61f19e66be55..b770335c03c1 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -954,7 +954,7 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct sock *sk, } - pctx = kmalloc(sizeof(struct pdp_ctx), GFP_KERNEL); + pctx = kmalloc(sizeof(*pctx), GFP_ATOMIC); if (pctx == NULL) return -ENOMEM; -- 2.20.1

1 0

[PATCH AUTOSEL 5.2 244/249] gtp: fix suspicious RCU usage
by Sasha Levin 15 Jul '19

15 Jul '19

From: Taehee Yoo <ap420073(a)gmail.com> [ Upstream commit e198987e7dd7d3645a53875151cd6f8fc425b706 ] gtp_encap_enable_socket() and gtp_encap_destroy() are not protected by rcu_read_lock(). and it's not safe to write sk->sk_user_data. This patch make these functions to use lock_sock() instead of rcu_dereference_sk_user_data(). Test commands: gtp-link add gtp1 Splat looks like: [ 83.238315] ============================= [ 83.239127] WARNING: suspicious RCU usage [ 83.239702] 5.2.0-rc6+ #49 Not tainted [ 83.240268] ----------------------------- [ 83.241205] drivers/net/gtp.c:799 suspicious rcu_dereference_check() usage! [ 83.243828] [ 83.243828] other info that might help us debug this: [ 83.243828] [ 83.246325] [ 83.246325] rcu_scheduler_active = 2, debug_locks = 1 [ 83.247314] 1 lock held by gtp-link/1008: [ 83.248523] #0: 0000000017772c7f (rtnl_mutex){+.+.}, at: __rtnl_newlink+0x5f5/0x11b0 [ 83.251503] [ 83.251503] stack backtrace: [ 83.252173] CPU: 0 PID: 1008 Comm: gtp-link Not tainted 5.2.0-rc6+ #49 [ 83.253271] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 83.254562] Call Trace: [ 83.254995] dump_stack+0x7c/0xbb [ 83.255567] gtp_encap_enable_socket+0x2df/0x360 [gtp] [ 83.256415] ? gtp_find_dev+0x1a0/0x1a0 [gtp] [ 83.257161] ? memset+0x1f/0x40 [ 83.257843] gtp_newlink+0x90/0xa21 [gtp] [ 83.258497] ? __netlink_ns_capable+0xc3/0xf0 [ 83.259260] __rtnl_newlink+0xb9f/0x11b0 [ 83.260022] ? rtnl_link_unregister+0x230/0x230 [ ... ] Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional") Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> Signed-off-by: David S. Miller <davem(a)davemloft.net> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- drivers/net/gtp.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 01fc51892e48..61f19e66be55 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -289,12 +289,14 @@ static void gtp_encap_destroy(struct sock *sk) { struct gtp_dev *gtp; - gtp = rcu_dereference_sk_user_data(sk); + lock_sock(sk); + gtp = sk->sk_user_data; if (gtp) { udp_sk(sk)->encap_type = 0; rcu_assign_sk_user_data(sk, NULL); sock_put(sk); } + release_sock(sk); } static void gtp_encap_disable_sock(struct sock *sk) @@ -796,7 +798,8 @@ static struct sock *gtp_encap_enable_socket(int fd, int type, goto out_sock; } - if (rcu_dereference_sk_user_data(sock->sk)) { + lock_sock(sock->sk); + if (sock->sk->sk_user_data) { sk = ERR_PTR(-EBUSY); goto out_sock; } @@ -812,6 +815,7 @@ static struct sock *gtp_encap_enable_socket(int fd, int type, setup_udp_tunnel_sock(sock_net(sock->sk), sock, &tuncfg); out_sock: + release_sock(sock->sk); sockfd_put(sock); return sk; } -- 2.20.1

1 0

[PATCH AUTOSEL 5.2 242/249] gtp: add missing gtp_encap_disable_sock() in gtp_encap_enable()
by Sasha Levin 15 Jul '19

15 Jul '19

From: Taehee Yoo <ap420073(a)gmail.com> [ Upstream commit e30155fd23c9c141cbe7d99b786e10a83a328837 ] If an invalid role is sent from user space, gtp_encap_enable() will fail. Then, it should call gtp_encap_disable_sock() but current code doesn't. It makes memory leak. Fixes: 91ed81f9abc7 ("gtp: support SGSN-side tunnels") Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> Signed-off-by: David S. Miller <davem(a)davemloft.net> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- drivers/net/gtp.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index fc45b749db46..01fc51892e48 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -843,8 +843,13 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[]) if (data[IFLA_GTP_ROLE]) { role = nla_get_u32(data[IFLA_GTP_ROLE]); - if (role > GTP_ROLE_SGSN) + if (role > GTP_ROLE_SGSN) { + if (sk0) + gtp_encap_disable_sock(sk0); + if (sk1u) + gtp_encap_disable_sock(sk1u); return -EINVAL; + } } gtp->sk0 = sk0; -- 2.20.1

1 0

[PATCH net 0/6] gtp: fix several bugs
by Taehee Yoo 08 Jul '19

08 Jul '19

This patch series fixes several bugs in the gtp module. First patch fixes suspicious RCU usage. The problem is to use rcu_dereference_sk_user_data() outside of RCU read critical section. Second patch fixes use-after-free. gtp_encap_destroy() is called twice. gtp_encap_destroy() use both gtp->sk0 and gtp->sk1u. these pointers can be freed in gtp_encap_destroy(). So, gtp_encap_destroy() should avoid using freed sk pointer. Third patch removes duplicate code in gtp_dellink(). gtp_dellink() calls gtp_encap_disable() twice. So, remove one of them. Fourth patch fixes usage of GFP_KERNEL. GFP_KERNEL can not be used in RCU read critical section. This patch make ipv4_pdp_add() to use GFP_ATOMIC instead of GFP_KERNEL. Fifth patch fixes use-after-free in gtp_newlink(). gtp_newlink() uses gtp_net which would be destroyed by the __exit_net routine. So, gtp_newlink should not be called after the __exit_net routine. Sixth patch adds missing error handling routine in gtp_encap_enable(). gtp_encap_enable() will fail, if invalid role value is sent from user-space. if so, gtp_encap_enable() should execute error handling routine. Taehee Yoo (6): gtp: fix suspicious RCU usage gtp: fix use-after-free in gtp_encap_destroy() gtp: remove duplicate code in gtp_dellink() gtp: fix Illegal context switch in RCU read-side critical section. gtp: fix use-after-free in gtp_newlink() gtp: add missing gtp_encap_disable_sock() in gtp_encap_enable() drivers/net/gtp.c | 37 +++++++++++++++++++++++++++++-------- 1 file changed, 29 insertions(+), 8 deletions(-) -- 2.17.1

3 3

[PATCH net 6/6] gtp: add missing gtp_encap_disable_sock() in gtp_encap_enable()
by Taehee Yoo 02 Jul '19

02 Jul '19

If an invalid role is sent from user space, gtp_encap_enable() will fail. Then, it should call gtp_encap_disable_sock() but current code doesn't. It makes memory leak. Fixes: 91ed81f9abc7 ("gtp: support SGSN-side tunnels") Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> --- drivers/net/gtp.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index b3ccac54e204..ecfe26215935 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -857,8 +857,13 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[]) if (data[IFLA_GTP_ROLE]) { role = nla_get_u32(data[IFLA_GTP_ROLE]); - if (role > GTP_ROLE_SGSN) + if (role > GTP_ROLE_SGSN) { + if (sk0) + gtp_encap_disable_sock(sk0); + if (sk1u) + gtp_encap_disable_sock(sk1u); return -EINVAL; + } } gtp->sk0 = sk0; -- 2.17.1

1 0

[PATCH net 5/6] gtp: fix use-after-free in gtp_newlink()
by Taehee Yoo 02 Jul '19

02 Jul '19

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(a)gmail.com> --- 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 52f35cbeb1dc..b3ccac54e204 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1376,9 +1376,9 @@ 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"); } -- 2.17.1

1 0

[PATCH net 4/6] gtp: fix Illegal context switch in RCU read-side critical section.
by Taehee Yoo 02 Jul '19

02 Jul '19

ipv4_pdp_add() is called in RCU read-side critical section. So GFP_KERNEL should not be used in the function. This patch make ipv4_pdp_add() to use GFP_ATOMIC instead of GFP_KERNEL. Test commands: gtp-link add gtp1 & gtp-tunnel add gtp1 v1 100 200 1.1.1.1 2.2.2.2 Splat looks like: [ 130.618881] ============================= [ 130.626382] WARNING: suspicious RCU usage [ 130.626994] 5.2.0-rc6+ #50 Not tainted [ 130.627622] ----------------------------- [ 130.628223] ./include/linux/rcupdate.h:266 Illegal context switch in RCU read-side critical section! [ 130.629684] [ 130.629684] other info that might help us debug this: [ 130.629684] [ 130.631022] [ 130.631022] rcu_scheduler_active = 2, debug_locks = 1 [ 130.632136] 4 locks held by gtp-tunnel/1025: [ 130.632925] #0: 000000002b93c8b7 (cb_lock){++++}, at: genl_rcv+0x15/0x40 [ 130.634159] #1: 00000000f17bc999 (genl_mutex){+.+.}, at: genl_rcv_msg+0xfb/0x130 [ 130.635487] #2: 00000000c644ed8e (rtnl_mutex){+.+.}, at: gtp_genl_new_pdp+0x18c/0x1150 [gtp] [ 130.636936] #3: 0000000007a1cde7 (rcu_read_lock){....}, at: gtp_genl_new_pdp+0x187/0x1150 [gtp] [ 130.638348] [ 130.638348] stack backtrace: [ 130.639062] CPU: 1 PID: 1025 Comm: gtp-tunnel Not tainted 5.2.0-rc6+ #50 [ 130.641318] Call Trace: [ 130.641707] dump_stack+0x7c/0xbb [ 130.642252] ___might_sleep+0x2c0/0x3b0 [ 130.642862] kmem_cache_alloc_trace+0x1cd/0x2b0 [ 130.643591] gtp_genl_new_pdp+0x6c5/0x1150 [gtp] [ 130.644371] genl_family_rcv_msg+0x63a/0x1030 [ 130.645074] ? mutex_lock_io_nested+0x1090/0x1090 [ 130.645845] ? genl_unregister_family+0x630/0x630 [ 130.646592] ? debug_show_all_locks+0x2d0/0x2d0 [ 130.647293] ? check_flags.part.40+0x440/0x440 [ 130.648099] genl_rcv_msg+0xa3/0x130 [ ... ] Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> --- 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 92ef777a757f..52f35cbeb1dc 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -959,7 +959,7 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct sock *sk, } - pctx = kmalloc(sizeof(struct pdp_ctx), GFP_KERNEL); + pctx = kmalloc(sizeof(*pctx), GFP_ATOMIC); if (pctx == NULL) return -ENOMEM; -- 2.17.1

1 0

[PATCH net 3/6] gtp: remove duplicate code in gtp_dellink()
by Taehee Yoo 02 Jul '19

02 Jul '19

gtp_encap_disable() in gtp_dellink() is unnecessary because it will be called by unregister_netdevice(). unregister_netdevice() internally calls gtp_dev_uninit() by ->ndo_uninit(). And gtp_dev_uninit() calls gtp_encap_disable(). Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> --- drivers/net/gtp.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 5101f8c3c99c..92ef777a757f 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -694,7 +694,6 @@ static void gtp_dellink(struct net_device *dev, struct list_head *head) { struct gtp_dev *gtp = netdev_priv(dev); - gtp_encap_disable(gtp); gtp_hashtable_free(gtp); list_del_rcu(&gtp->list); unregister_netdevice_queue(dev, head); -- 2.17.1

1 0

[PATCH net 2/6] gtp: fix use-after-free in gtp_encap_destroy()
by Taehee Yoo 02 Jul '19

02 Jul '19

gtp_encap_destroy() is called twice. 1. When interface is deleted. 2. When udp socket is destroyed. either gtp->sk0 or gtp->sk1u could be freed by sock_put() in gtp_encap_destroy(). so, when gtp_encap_destroy() is called again, it would uses freed sk pointer. patch makes gtp_encap_destroy() to set either gtp->sk0 or gtp->sk1u to null. in addition, both gtp->sk0 and gtp->sk1u pointer are protected by rtnl_lock. so, rtnl_lock() is added. Test command: gtp-link add gtp1 & killall gtp-link ip link del gtp1 Splat looks like: [ 83.182767] BUG: KASAN: use-after-free in __lock_acquire+0x3a20/0x46a0 [ 83.184128] Read of size 8 at addr ffff8880cc7d5360 by task ip/1008 [ 83.185567] CPU: 1 PID: 1008 Comm: ip Not tainted 5.2.0-rc6+ #50 [ 83.188469] Call Trace: [ ... ] [ 83.200126] lock_acquire+0x141/0x380 [ 83.200575] ? lock_sock_nested+0x3a/0xf0 [ 83.201069] _raw_spin_lock_bh+0x38/0x70 [ 83.201551] ? lock_sock_nested+0x3a/0xf0 [ 83.202044] lock_sock_nested+0x3a/0xf0 [ 83.202520] gtp_encap_destroy+0x18/0xe0 [gtp] [ 83.203065] gtp_encap_disable.isra.14+0x13/0x50 [gtp] [ 83.203687] gtp_dellink+0x56/0x170 [gtp] [ 83.204190] rtnl_delete_link+0xb4/0x100 [ ... ] [ 83.236513] Allocated by task 976: [ 83.236925] save_stack+0x19/0x80 [ 83.237332] __kasan_kmalloc.constprop.3+0xa0/0xd0 [ 83.237894] kmem_cache_alloc+0xd8/0x280 [ 83.238360] sk_prot_alloc.isra.42+0x50/0x200 [ 83.238874] sk_alloc+0x32/0x940 [ 83.239264] inet_create+0x283/0xc20 [ 83.239684] __sock_create+0x2dd/0x540 [ 83.240136] __sys_socket+0xca/0x1a0 [ 83.240550] __x64_sys_socket+0x6f/0xb0 [ 83.240998] do_syscall_64+0x9c/0x450 [ 83.241466] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 83.242061] [ 83.242249] Freed by task 0: [ 83.242616] save_stack+0x19/0x80 [ 83.243013] __kasan_slab_free+0x111/0x150 [ 83.243498] kmem_cache_free+0x89/0x250 [ 83.244444] __sk_destruct+0x38f/0x5a0 [ 83.245366] rcu_core+0x7e9/0x1c20 [ 83.245766] __do_softirq+0x213/0x8fa Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional") Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> --- drivers/net/gtp.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 939da5442f65..5101f8c3c99c 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -285,13 +285,17 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb) return gtp_rx(pctx, skb, hdrlen, gtp->role); } -static void gtp_encap_destroy(struct sock *sk) +static void __gtp_encap_destroy(struct sock *sk) { struct gtp_dev *gtp; lock_sock(sk); gtp = sk->sk_user_data; if (gtp) { + if (gtp->sk0 == sk) + gtp->sk0 = NULL; + else + gtp->sk1u = NULL; udp_sk(sk)->encap_type = 0; rcu_assign_sk_user_data(sk, NULL); sock_put(sk); @@ -299,12 +303,19 @@ static void gtp_encap_destroy(struct sock *sk) release_sock(sk); } +static void gtp_encap_destroy(struct sock *sk) +{ + rtnl_lock(); + __gtp_encap_destroy(sk); + rtnl_unlock(); +} + static void gtp_encap_disable_sock(struct sock *sk) { if (!sk) return; - gtp_encap_destroy(sk); + __gtp_encap_destroy(sk); } static void gtp_encap_disable(struct gtp_dev *gtp) @@ -1038,6 +1049,7 @@ static int gtp_genl_new_pdp(struct sk_buff *skb, struct genl_info *info) return -EINVAL; } + rtnl_lock(); rcu_read_lock(); gtp = gtp_find_dev(sock_net(skb->sk), info->attrs); @@ -1062,6 +1074,7 @@ static int gtp_genl_new_pdp(struct sk_buff *skb, struct genl_info *info) out_unlock: rcu_read_unlock(); + rtnl_unlock(); return err; } -- 2.17.1

1 0

[PATCH net 1/6] gtp: fix suspicious RCU usage
by Taehee Yoo 02 Jul '19

02 Jul '19

gtp_encap_enable_socket() and gtp_encap_destroy() are not protected by rcu_read_lock(). and it's not safe to write sk->sk_user_data. This patch make these functions to use lock_sock() instead of rcu_dereference_sk_user_data(). Test commands: gtp-link add gtp1 Splat looks like: [ 83.238315] ============================= [ 83.239127] WARNING: suspicious RCU usage [ 83.239702] 5.2.0-rc6+ #49 Not tainted [ 83.240268] ----------------------------- [ 83.241205] drivers/net/gtp.c:799 suspicious rcu_dereference_check() usage! [ 83.243828] [ 83.243828] other info that might help us debug this: [ 83.243828] [ 83.246325] [ 83.246325] rcu_scheduler_active = 2, debug_locks = 1 [ 83.247314] 1 lock held by gtp-link/1008: [ 83.248523] #0: 0000000017772c7f (rtnl_mutex){+.+.}, at: __rtnl_newlink+0x5f5/0x11b0 [ 83.251503] [ 83.251503] stack backtrace: [ 83.252173] CPU: 0 PID: 1008 Comm: gtp-link Not tainted 5.2.0-rc6+ #49 [ 83.253271] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 83.254562] Call Trace: [ 83.254995] dump_stack+0x7c/0xbb [ 83.255567] gtp_encap_enable_socket+0x2df/0x360 [gtp] [ 83.256415] ? gtp_find_dev+0x1a0/0x1a0 [gtp] [ 83.257161] ? memset+0x1f/0x40 [ 83.257843] gtp_newlink+0x90/0xa21 [gtp] [ 83.258497] ? __netlink_ns_capable+0xc3/0xf0 [ 83.259260] __rtnl_newlink+0xb9f/0x11b0 [ 83.260022] ? rtnl_link_unregister+0x230/0x230 [ ... ] Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional") Signed-off-by: Taehee Yoo <ap420073(a)gmail.com> --- drivers/net/gtp.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index fc45b749db46..939da5442f65 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -289,12 +289,14 @@ static void gtp_encap_destroy(struct sock *sk) { struct gtp_dev *gtp; - gtp = rcu_dereference_sk_user_data(sk); + lock_sock(sk); + gtp = sk->sk_user_data; if (gtp) { udp_sk(sk)->encap_type = 0; rcu_assign_sk_user_data(sk, NULL); sock_put(sk); } + release_sock(sk); } static void gtp_encap_disable_sock(struct sock *sk) @@ -796,7 +798,8 @@ static struct sock *gtp_encap_enable_socket(int fd, int type, goto out_sock; } - if (rcu_dereference_sk_user_data(sock->sk)) { + lock_sock(sock->sk); + if (sock->sk->sk_user_data) { sk = ERR_PTR(-EBUSY); goto out_sock; } @@ -812,6 +815,7 @@ static struct sock *gtp_encap_enable_socket(int fd, int type, setup_udp_tunnel_sock(sock_net(sock->sk), sock, &tuncfg); out_sock: + release_sock(sock->sk); sockfd_put(sock); return sk; } -- 2.17.1

1 0

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