net/sched: fix NULL dereference in the error path of .init()

with several TC actions it's possible to see NULL pointer dereference, when the .init() function calls tcf_idr_alloc(), fails at some point and then calls tcf_idr_release(): this series fixes all them introducing non-NULL tests in the .cleanup() function.

Davide Caratti (5):
net/sched: fix NULL dereference in the error path of tcf_vlan_init() net/sched: fix NULL dereference in the error path of tcf_csum_init() net/sched: fix NULL dereference in the error path of tunnel_key_init() net/sched: fix NULL dereference in the error path of tcf_sample_init() net/sched: fix NULL dereference on the error path of tcf_skbmod_init()

 net/sched/act_csum.c       | 3 ++-
 net/sched/act_sample.c     | 3 ++-
 net/sched/act_skbmod.c     | 3 ++-
 net/sched/act_tunnel_key.c | 9 +++++----
 net/sched/act_vlan.c       | 3 ++-
 5 files changed, 13 insertions(+), 8 deletions(-)

2.14.3

when the following command

 # tc actions replace action vlan pop index 100

is run for the first time, and tcf_vlan_init() fails allocating struct tcf_vlan_params, tcf_vlan_cleanup() calls kfree_rcu(NULL, ...). This causes the following error:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
 IP: __call_rcu+0x23/0x2b0
 PGD 80000000760a2067 P4D 80000000760a2067 PUD 742c1067 PMD 0
 Oops: 0002 [#1] SMP PTI
 Modules linked in: act_vlan(E) ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 snd_hda_codec_generic snd_hda_intel mbcache snd_hda_codec jbd2 snd_hda_core crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc snd_hwdep snd_seq snd_seq_device snd_pcm aesni_intel crypto_simd snd_timer glue_helper snd cryptd joydev soundcore virtio_balloon pcspkr i2c_piix4 nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm virtio_console virtio_blk virtio_net ata_piix crc32c_intel libata virtio_pci i2c_core virtio_ring serio_raw virtio floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_vlan]
 CPU: 3 PID: 3119 Comm: tc Tainted: G            E    4.16.0-rc4.act_vlan.orig+ #403
 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
 RIP: 0010:__call_rcu+0x23/0x2b0
 RSP: 0018:ffffaac3005fb798 EFLAGS: 00010246
 RAX: ffffffffc0704080 RBX: ffff97f2b4bbe900 RCX: 00000000ffffffff
 RDX: ffffffffabca5f00 RSI: 0000000000000010 RDI: 0000000000000010
 RBP: 0000000000000010 R08: 0000000000000001 R09: 0000000000000044
 R10: 00000000fd003000 R11: ffff97f2faab5b91 R12: 0000000000000000
 R13: ffffffffabca5f00 R14: ffff97f2fb80202c R15: 00000000fffffff4
 FS:  00007f68f75b4740(0000) GS:ffff97f2ffd80000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000018 CR3: 0000000072b52001 CR4: 00000000001606e0
 Call Trace:
  __tcf_idr_release+0x79/0xf0
  tcf_vlan_init+0x168/0x270 [act_vlan]
  tcf_action_init_1+0x2cc/0x430
  tcf_action_init+0xd3/0x1b0
  tc_ctl_action+0x18b/0x240
  rtnetlink_rcv_msg+0x29c/0x310
  ? _cond_resched+0x15/0x30
  ? __kmalloc_node_track_caller+0x1b9/0x270
  ? rtnl_calcit.isra.28+0x100/0x100
  netlink_rcv_skb+0xd2/0x110
  netlink_unicast+0x17c/0x230
  netlink_sendmsg+0x2cd/0x3c0
  sock_sendmsg+0x30/0x40
  ___sys_sendmsg+0x27a/0x290
  ? filemap_map_pages+0x34a/0x3a0
  ? __handle_mm_fault+0xbfd/0xe20
  __sys_sendmsg+0x51/0x90
  do_syscall_64+0x6e/0x1a0
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
 RIP: 0033:0x7f68f69c5ba0
 RSP: 002b:00007fffd79c1118 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
 RAX: ffffffffffffffda RBX: 00007fffd79c1240 RCX: 00007f68f69c5ba0
 RDX: 0000000000000000 RSI: 00007fffd79c1190 RDI: 0000000000000003
 RBP: 000000005aaa708e R08: 0000000000000002 R09: 0000000000000000
 R10: 00007fffd79c0ba0 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007fffd79c1254 R14: 0000000000000001 R15: 0000000000669f60
 Code: 5d e9 42 da ff ff 66 90 0f 1f 44 00 00 41 57 41 56 41 55 49 89 d5 41 54 55 48 89 fd 53 48 83 ec 08 40 f6 c7 07 0f 85 19 02 00 00 <48> 89 75 08 48 c7 45 00 00 00 00 00 9c 58 0f 1f 44 00 00 49 89
 RIP: __call_rcu+0x23/0x2b0 RSP: ffffaac3005fb798
 CR2: 0000000000000018

fix this in tcf_vlan_cleanup(), ensuring that kfree_rcu(p, ...) is called only when p is not NULL.

---
 net/sched/act_vlan.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index e1a1b3f3983a..c2914e9a4a6f 100644
@@ -225,7 +225,8 @@ static void tcf_vlan_cleanup(struct tc_action *a)
 	struct tcf_vlan_params *p;
 
 	p = rcu_dereference_protected(v->vlan_p, 1);
-	kfree_rcu(p, rcu);
+	if (p)
+		kfree_rcu(p, rcu);
 }
 
 static int tcf_vlan_dump(struct sk_buff *skb, struct tc_action *a,

2.14.3

when the following command

 # tc action add action csum udp continue index 100

is run for the first time, and tcf_csum_init() fails allocating struct tcf_csum, tcf_csum_cleanup() calls kfree_rcu(NULL,...). This causes the following error:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
 IP: __call_rcu+0x23/0x2b0
 PGD 80000000740b4067 P4D 80000000740b4067 PUD 32e7f067 PMD 0
 Oops: 0002 [#1] SMP PTI
 Modules linked in: act_csum(E) act_vlan ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 mbcache jbd2 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_generic pcbc snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer aesni_intel crypto_simd glue_helper cryptd snd joydev pcspkr virtio_balloon i2c_piix4 soundcore nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm virtio_blk drm virtio_net virtio_console ata_piix crc32c_intel libata virtio_pci serio_raw i2c_core virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_vlan]
 CPU: 2 PID: 5763 Comm: tc Tainted: G            E    4.16.0-rc4.act_vlan.orig+ #403
 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
 RIP: 0010:__call_rcu+0x23/0x2b0
 RSP: 0018:ffffb275803e77c0 EFLAGS: 00010246
 RAX: ffffffffc057b080 RBX: ffff9674bc6f5240 RCX: 00000000ffffffff
 RDX: ffffffff928a5f00 RSI: 0000000000000008 RDI: 0000000000000008
 RBP: 0000000000000008 R08: 0000000000000001 R09: 0000000000000044
 R10: 0000000000000220 R11: ffff9674b9ab4821 R12: 0000000000000000
 R13: ffffffff928a5f00 R14: 0000000000000000 R15: 0000000000000001
 FS:  00007fa6368d8740(0000) GS:ffff9674bfd00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000010 CR3: 0000000073dec001 CR4: 00000000001606e0
 Call Trace:
  __tcf_idr_release+0x79/0xf0
  tcf_csum_init+0xfb/0x180 [act_csum]
  tcf_action_init_1+0x2cc/0x430
  tcf_action_init+0xd3/0x1b0
  tc_ctl_action+0x18b/0x240
  rtnetlink_rcv_msg+0x29c/0x310
  ? _cond_resched+0x15/0x30
  ? __kmalloc_node_track_caller+0x1b9/0x270
  ? rtnl_calcit.isra.28+0x100/0x100
  netlink_rcv_skb+0xd2/0x110
  netlink_unicast+0x17c/0x230
  netlink_sendmsg+0x2cd/0x3c0
  sock_sendmsg+0x30/0x40
  ___sys_sendmsg+0x27a/0x290
  ? filemap_map_pages+0x34a/0x3a0
  ? __handle_mm_fault+0xbfd/0xe20
  __sys_sendmsg+0x51/0x90
  do_syscall_64+0x6e/0x1a0
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
 RIP: 0033:0x7fa635ce9ba0
 RSP: 002b:00007ffc185b0fc8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
 RAX: ffffffffffffffda RBX: 00007ffc185b10f0 RCX: 00007fa635ce9ba0
 RDX: 0000000000000000 RSI: 00007ffc185b1040 RDI: 0000000000000003
 RBP: 000000005aaa85e0 R08: 0000000000000002 R09: 0000000000000000
 R10: 00007ffc185b0a20 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007ffc185b1104 R14: 0000000000000001 R15: 0000000000669f60
 Code: 5d e9 42 da ff ff 66 90 0f 1f 44 00 00 41 57 41 56 41 55 49 89 d5 41 54 55 48 89 fd 53 48 83 ec 08 40 f6 c7 07 0f 85 19 02 00 00 <48> 89 75 08 48 c7 45 00 00 00 00 00 9c 58 0f 1f 44 00 00 49 89
 RIP: __call_rcu+0x23/0x2b0 RSP: ffffb275803e77c0
 CR2: 0000000000000010

fix this in tcf_csum_cleanup(), ensuring that kfree_rcu(param, ...) is called only when param is not NULL.

---
 net/sched/act_csum.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 24b2e8e681cf..2a5c8fd860cf 100644
@@ -626,7 +626,8 @@ static void tcf_csum_cleanup(struct tc_action *a)
 	struct tcf_csum_params *params;
 
 	params = rcu_dereference_protected(p->params, 1);
-	kfree_rcu(params, rcu);
+	if (params)
+		kfree_rcu(params, rcu);
 }
 
 static int tcf_csum_walker(struct net *net, struct sk_buff *skb,

2.14.3

when the following command

 # tc action add action tunnel_key unset index 100

is run for the first time, and tunnel_key_init() fails to allocate struct tcf_tunnel_key_params, tunnel_key_release() dereferences NULL pointers. This causes the following error:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
 IP: tunnel_key_release+0xd/0x40 [act_tunnel_key]
 PGD 8000000033787067 P4D 8000000033787067 PUD 74646067 PMD 0
 Oops: 0000 [#1] SMP PTI
 Modules linked in: act_tunnel_key(E) act_csum ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 mbcache jbd2 crct10dif_pclmul crc32_pclmul snd_hda_codec_generic ghash_clmulni_intel snd_hda_intel pcbc snd_hda_codec snd_hda_core snd_hwdep snd_seq aesni_intel snd_seq_device crypto_simd glue_helper snd_pcm cryptd joydev snd_timer pcspkr virtio_balloon snd i2c_piix4 soundcore nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm virtio_net virtio_blk drm virtio_console crc32c_intel ata_piix serio_raw i2c_core virtio_pci libata virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod
 CPU: 2 PID: 3101 Comm: tc Tainted: G            E    4.16.0-rc4.act_vlan.orig+ #403
 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
 RIP: 0010:tunnel_key_release+0xd/0x40 [act_tunnel_key]
 RSP: 0018:ffffba46803b7768 EFLAGS: 00010286
 RAX: ffffffffc09010a0 RBX: 0000000000000000 RCX: 0000000000000024
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff99ee336d7480
 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000044
 R10: 0000000000000220 R11: ffff99ee79d73131 R12: 0000000000000000
 R13: ffff99ee32d67610 R14: ffff99ee7671dc38 R15: 00000000fffffff4
 FS:  00007febcb2cd740(0000) GS:ffff99ee7fd00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000010 CR3: 000000007c8e4005 CR4: 00000000001606e0
 Call Trace:
  __tcf_idr_release+0x79/0xf0
  tunnel_key_init+0xd9/0x460 [act_tunnel_key]
  tcf_action_init_1+0x2cc/0x430
  tcf_action_init+0xd3/0x1b0
  tc_ctl_action+0x18b/0x240
  rtnetlink_rcv_msg+0x29c/0x310
  ? _cond_resched+0x15/0x30
  ? __kmalloc_node_track_caller+0x1b9/0x270
  ? rtnl_calcit.isra.28+0x100/0x100
  netlink_rcv_skb+0xd2/0x110
  netlink_unicast+0x17c/0x230
  netlink_sendmsg+0x2cd/0x3c0
  sock_sendmsg+0x30/0x40
  ___sys_sendmsg+0x27a/0x290
  __sys_sendmsg+0x51/0x90
  do_syscall_64+0x6e/0x1a0
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
 RIP: 0033:0x7febca6deba0
 RSP: 002b:00007ffe7b0dd128 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
 RAX: ffffffffffffffda RBX: 00007ffe7b0dd250 RCX: 00007febca6deba0
 RDX: 0000000000000000 RSI: 00007ffe7b0dd1a0 RDI: 0000000000000003
 RBP: 000000005aaa90cb R08: 0000000000000002 R09: 0000000000000000
 R10: 00007ffe7b0dcba0 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007ffe7b0dd264 R14: 0000000000000001 R15: 0000000000669f60
 Code: 44 00 00 8b 0d b5 23 00 00 48 8b 87 48 10 00 00 48 8b 3c c8 e9 a5 e5 d8 c3 0f 1f 44 00 00 0f 1f 44 00 00 53 48 8b 9f b0 00 00 00 <83> 7b 10 01 74 0b 48 89 df 31 f6 5b e9 f2 fa 7f c3 48 8b 7b 18
 RIP: tunnel_key_release+0xd/0x40 [act_tunnel_key] RSP: ffffba46803b7768
 CR2: 0000000000000010

Fix this in tunnel_key_release(), ensuring 'param' is not NULL before dereferencing it.

---
 net/sched/act_tunnel_key.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

index 0e23aac09ad6..5dd819840feb 100644
@@ -207,11 +207,12 @@ static void tunnel_key_release(struct tc_action *a)
 	struct tcf_tunnel_key_params *params;
 
 	params = rcu_dereference_protected(t->params, 1);
+	if (params) {
+		if (params->tcft_action == TCA_TUNNEL_KEY_ACT_SET)
+			dst_release(&params->tcft_enc_metadata->dst);
 
-	if (params->tcft_action == TCA_TUNNEL_KEY_ACT_SET)
-		dst_release(&params->tcft_enc_metadata->dst);
-
-	kfree_rcu(params, rcu);
+		kfree_rcu(params, rcu);
+	}
 }
 
 static int tunnel_key_dump_addresses(struct sk_buff *skb,

2.14.3

when the following command

 # tc action add action sample rate 100 group 100 index 100

is run for the first time, and psample_group_get(100) fails to create a new group, tcf_sample_cleanup() calls psample_group_put(NULL), thus causing the following error:

 BUG: unable to handle kernel NULL pointer dereference at 000000000000001c
 IP: psample_group_put+0x15/0x71 [psample]
 PGD 8000000075775067 P4D 8000000075775067 PUD 7453c067 PMD 0
 Oops: 0002 [#1] SMP PTI
 Modules linked in: act_sample(E) psample ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core mbcache jbd2 crct10dif_pclmul snd_hwdep crc32_pclmul snd_seq ghash_clmulni_intel pcbc snd_seq_device snd_pcm aesni_intel crypto_simd snd_timer glue_helper snd cryptd joydev pcspkr i2c_piix4 soundcore virtio_balloon nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm virtio_net ata_piix virtio_console virtio_blk libata serio_raw crc32c_intel virtio_pci i2c_core virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_tunnel_key]
 CPU: 2 PID: 5740 Comm: tc Tainted: G            E    4.16.0-rc4.act_vlan.orig+ #403
 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
 RIP: 0010:psample_group_put+0x15/0x71 [psample]
 RSP: 0018:ffffb8a80032f7d0 EFLAGS: 00010246
 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000024
 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffffc06d93c0
 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000044
 R10: 00000000bd003000 R11: ffff979fba04aa59 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: ffff979fbba3f22c
 FS:  00007f7638112740(0000) GS:ffff979fbfd00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000000000000001c CR3: 00000000734ea001 CR4: 00000000001606e0
 Call Trace:
  __tcf_idr_release+0x79/0xf0
  tcf_sample_init+0x125/0x1d0 [act_sample]
  tcf_action_init_1+0x2cc/0x430
  tcf_action_init+0xd3/0x1b0
  tc_ctl_action+0x18b/0x240
  rtnetlink_rcv_msg+0x29c/0x310
  ? _cond_resched+0x15/0x30
  ? __kmalloc_node_track_caller+0x1b9/0x270
  ? rtnl_calcit.isra.28+0x100/0x100
  netlink_rcv_skb+0xd2/0x110
  netlink_unicast+0x17c/0x230
  netlink_sendmsg+0x2cd/0x3c0
  sock_sendmsg+0x30/0x40
  ___sys_sendmsg+0x27a/0x290
  ? filemap_map_pages+0x34a/0x3a0
  ? __handle_mm_fault+0xbfd/0xe20
  __sys_sendmsg+0x51/0x90
  do_syscall_64+0x6e/0x1a0
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
 RIP: 0033:0x7f7637523ba0
 RSP: 002b:00007fff0473ef58 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
 RAX: ffffffffffffffda RBX: 00007fff0473f080 RCX: 00007f7637523ba0
 RDX: 0000000000000000 RSI: 00007fff0473efd0 RDI: 0000000000000003
 RBP: 000000005aaaac80 R08: 0000000000000002 R09: 0000000000000000
 R10: 00007fff0473e9e0 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007fff0473f094 R14: 0000000000000001 R15: 0000000000669f60
 Code: be 02 00 00 00 48 89 df e8 a9 fe ff ff e9 7c ff ff ff 0f 1f 40 00 0f 1f 44 00 00 53 48 89 fb 48 c7 c7 c0 93 6d c0 e8 db 20 8c ef <83> 6b 1c 01 74 10 48 c7 c7 c0 93 6d c0 ff 14 25 e8 83 83 b0 5b
 RIP: psample_group_put+0x15/0x71 [psample] RSP: ffffb8a80032f7d0
 CR2: 000000000000001c

Fix it in tcf_sample_cleanup(), ensuring that calls to psample_group_put(p) are done only when p is not NULL.

---
 net/sched/act_sample.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 1ba0df238756..74c5d7e6a0fa 100644
@@ -103,7 +103,8 @@ static void tcf_sample_cleanup(struct tc_action *a)
 
 	psample_group = rtnl_dereference(s->psample_group);
 	RCU_INIT_POINTER(s->psample_group, NULL);
-	psample_group_put(psample_group);
+	if (psample_group)
+		psample_group_put(psample_group);
 }
 
 static bool tcf_sample_dev_ok_push(struct net_device *dev)

2.14.3

when the following command

 # tc action replace action skbmod swap mac index 100

is run for the first time, and tcf_skbmod_init() fails to allocate struct tcf_skbmod_params, tcf_skbmod_cleanup() calls kfree_rcu(NULL), thus causing the following error:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
 IP: __call_rcu+0x23/0x2b0
 PGD 8000000034057067 P4D 8000000034057067 PUD 74937067 PMD 0
 Oops: 0002 [#1] SMP PTI
 Modules linked in: act_skbmod(E) psample ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 snd_hda_codec_generic snd_hda_intel snd_hda_codec crct10dif_pclmul mbcache jbd2 crc32_pclmul snd_hda_core ghash_clmulni_intel snd_hwdep pcbc snd_seq snd_seq_device snd_pcm aesni_intel snd_timer crypto_simd glue_helper snd cryptd virtio_balloon joydev soundcore pcspkr i2c_piix4 nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm virtio_console virtio_net virtio_blk ata_piix libata crc32c_intel virtio_pci serio_raw virtio_ring virtio i2c_core floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_skbmod]
 CPU: 3 PID: 3144 Comm: tc Tainted: G            E    4.16.0-rc4.act_vlan.orig+ #403
 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
 RIP: 0010:__call_rcu+0x23/0x2b0
 RSP: 0018:ffffbd2e403e7798 EFLAGS: 00010246
 RAX: ffffffffc0872080 RBX: ffff981d34bff780 RCX: 00000000ffffffff
 RDX: ffffffff922a5f00 RSI: 0000000000000000 RDI: 0000000000000000
 RBP: 0000000000000000 R08: 0000000000000001 R09: 000000000000021f
 R10: 000000003d003000 R11: 0000000000aaaaaa R12: 0000000000000000
 R13: ffffffff922a5f00 R14: 0000000000000001 R15: ffff981d3b698c2c
 FS:  00007f3678292740(0000) GS:ffff981d3fd80000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000008 CR3: 000000007c57a006 CR4: 00000000001606e0
 Call Trace:
  __tcf_idr_release+0x79/0xf0
  tcf_skbmod_init+0x1d1/0x210 [act_skbmod]
  tcf_action_init_1+0x2cc/0x430
  tcf_action_init+0xd3/0x1b0
  tc_ctl_action+0x18b/0x240
  rtnetlink_rcv_msg+0x29c/0x310
  ? _cond_resched+0x15/0x30
  ? __kmalloc_node_track_caller+0x1b9/0x270
  ? rtnl_calcit.isra.28+0x100/0x100
  netlink_rcv_skb+0xd2/0x110
  netlink_unicast+0x17c/0x230
  netlink_sendmsg+0x2cd/0x3c0
  sock_sendmsg+0x30/0x40
  ___sys_sendmsg+0x27a/0x290
  ? filemap_map_pages+0x34a/0x3a0
  ? __handle_mm_fault+0xbfd/0xe20
  __sys_sendmsg+0x51/0x90
  do_syscall_64+0x6e/0x1a0
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
 RIP: 0033:0x7f36776a3ba0
 RSP: 002b:00007fff4703b618 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
 RAX: ffffffffffffffda RBX: 00007fff4703b740 RCX: 00007f36776a3ba0
 RDX: 0000000000000000 RSI: 00007fff4703b690 RDI: 0000000000000003
 RBP: 000000005aaaba36 R08: 0000000000000002 R09: 0000000000000000
 R10: 00007fff4703b0a0 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007fff4703b754 R14: 0000000000000001 R15: 0000000000669f60
 Code: 5d e9 42 da ff ff 66 90 0f 1f 44 00 00 41 57 41 56 41 55 49 89 d5 41 54 55 48 89 fd 53 48 83 ec 08 40 f6 c7 07 0f 85 19 02 00 00 <48> 89 75 08 48 c7 45 00 00 00 00 00 9c 58 0f 1f 44 00 00 49 89
 RIP: __call_rcu+0x23/0x2b0 RSP: ffffbd2e403e7798
 CR2: 0000000000000008

Fix it in tcf_skbmod_cleanup(), ensuring that kfree_rcu(p, ...) is called only when p is not NULL.

---
 net/sched/act_skbmod.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index fa975262dbac..d09565d6433e 100644
@@ -190,7 +190,8 @@ static void tcf_skbmod_cleanup(struct tc_action *a)
 	struct tcf_skbmod_params  *p;
 
 	p = rcu_dereference_protected(d->skbmod_p, 1);
-	kfree_rcu(p, rcu);
+	if (p)
+		kfree_rcu(p, rcu);
 }
 
 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,

2.14.3

From: Davide Caratti <[email protected]>
Date: Fri, 16 Mar 2018 00:00:52 +0100

Series applied and queued up for -stable, thank you.