4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Davide Caratti <dcaratti@xxxxxxxxxx>
[ Upstream commit 34043d250f51368f214aed7f54c2dc29c819a8c7 ]
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 <mcroce@xxxxxxxxxx>
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 <mcroce@xxxxxxxxxx>
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
Acked-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/act_sample.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/sched/act_sample.c
+++ b/net/sched/act_sample.c
@@ -64,7 +64,7 @@ static int tcf_sample_init(struct net *n
if (!exists) {
ret = tcf_idr_create(tn, parm->index, est, a,
- &act_sample_ops, bind, false);
+ &act_sample_ops, bind, true);
if (ret)
return ret;
ret = ACT_P_CREATED;
