Fri, Sep 14, 2018 at 12:03:18PM CEST, dcara...@redhat.com wrote:
>Matteo reported the following splat, testing the datapath of TC 'sample':
>
> BUG: KASAN: null-ptr-deref in tcf_sample_act+0xc4/0x310
> Read of size 8 at addr 0000000000000000 by task nc/433
>
> CPU: 0 PID: 433 Comm: nc Not tainted 4.19.0-rc3-kvm #17
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> ?-20180531_142017-buildhw-08.phx2.fedoraproject.org-1.fc28 04/01/2014
> Call Trace:
> kasan_report.cold.6+0x6c/0x2fa
> tcf_sample_act+0xc4/0x310
> ? dev_hard_start_xmit+0x117/0x180
> tcf_action_exec+0xa3/0x160
> tcf_classify+0xdd/0x1d0
> htb_enqueue+0x18e/0x6b0
> ? deref_stack_reg+0x7a/0xb0
> ? htb_delete+0x4b0/0x4b0
> ? unwind_next_frame+0x819/0x8f0
> ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
> __dev_queue_xmit+0x722/0xca0
> ? unwind_get_return_address_ptr+0x50/0x50
> ? netdev_pick_tx+0xe0/0xe0
> ? save_stack+0x8c/0xb0
> ? kasan_kmalloc+0xbe/0xd0
> ? __kmalloc_track_caller+0xe4/0x1c0
> ? __kmalloc_reserve.isra.45+0x24/0x70
> ? __alloc_skb+0xdd/0x2e0
> ? sk_stream_alloc_skb+0x91/0x3b0
> ? tcp_sendmsg_locked+0x71b/0x15a0
> ? tcp_sendmsg+0x22/0x40
> ? __sys_sendto+0x1b0/0x250
> ? __x64_sys_sendto+0x6f/0x80
> ? do_syscall_64+0x5d/0x150
> ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
> ? __sys_sendto+0x1b0/0x250
> ? __x64_sys_sendto+0x6f/0x80
> ? do_syscall_64+0x5d/0x150
> ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
> ip_finish_output2+0x495/0x590
> ? ip_copy_metadata+0x2e0/0x2e0
> ? skb_gso_validate_network_len+0x6f/0x110
> ? ip_finish_output+0x174/0x280
> __tcp_transmit_skb+0xb17/0x12b0
> ? __tcp_select_window+0x380/0x380
> tcp_write_xmit+0x913/0x1de0
> ? __sk_mem_schedule+0x50/0x80
> tcp_sendmsg_locked+0x49d/0x15a0
> ? tcp_rcv_established+0x8da/0xa30
> ? tcp_set_state+0x220/0x220
> ? clear_user+0x1f/0x50
> ? iov_iter_zero+0x1ae/0x590
> ? __fget_light+0xa0/0xe0
> tcp_sendmsg+0x22/0x40
> __sys_sendto+0x1b0/0x250
> ? __ia32_sys_getpeername+0x40/0x40
> ? _copy_to_user+0x58/0x70
> ? poll_select_copy_remaining+0x176/0x200
> ? __pollwait+0x1c0/0x1c0
> ? ktime_get_ts64+0x11f/0x140
> ? kern_select+0x108/0x150
> ? core_sys_select+0x360/0x360
> ? vfs_read+0x127/0x150
> ? kernel_write+0x90/0x90
> __x64_sys_sendto+0x6f/0x80
> do_syscall_64+0x5d/0x150
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7fefef2b129d
> Code: ff ff ff ff eb b6 0f 1f 80 00 00 00 00 48 8d 05 51 37 0c 00 41 89 ca 8b
> 00 85 c0 75 20 45 31 c9 45 31 c0 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77
> 6b f3 c3 66 0f 1f 84 00 00 00 00 00 41 56 41
> RSP: 002b:00007fff2f5350c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 000056118d60c120 RCX: 00007fefef2b129d
> RDX: 0000000000002000 RSI: 000056118d629320 RDI: 0000000000000003
> RBP: 000056118d530370 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000002000
> R13: 000056118d5c2a10 R14: 000056118d5c2a10 R15: 000056118d5303b8
>
>tcf_sample_act() tried to update its per-cpu stats, but tcf_sample_init()
>forgot to allocate them, because tcf_idr_create() was called with a wrong
>value of 'cpustats'. Setting it to true proved to fix the reported crash.
>
>Reported-by: Matteo Croce <mcr...@redhat.com>
>Fixes: 65a206c01e8e ("net/sched: Change act_api and act_xxx modules to use
>IDR")
>Fixes: 5c5670fae430 ("net/sched: Introduce sample tc action")
>Tested-by: Matteo Croce <mcr...@redhat.com>
>Signed-off-by: Davide Caratti <dcara...@redhat.com>
Acked-by: Jiri Pirko <j...@mellanox.com>
