Fri, Mar 16, 2018 at 12:00:57AM CET, dcara...@redhat.com wrote: >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. > >Fixes: 86da71b57383 ("net_sched: Introduce skbmod action") >Signed-off-by: Davide Caratti <dcara...@redhat.com>
Acked-by: Jiri Pirko <j...@mellanox.com>