Fri, Mar 16, 2018 at 12:00:56AM CET, dcara...@redhat.com wrote:
>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.
>
>Fixes: cadb9c9fdbc6 ("net/sched: act_sample: Fix error path in init")
>Signed-off-by: Davide Caratti <dcara...@redhat.com>
Acked-by: Jiri Pirko <j...@mellanox.com>
