On Thursday, 30 January 2020 21:27:12 CET syzbot wrote: [...]
dashboard link: https://syzkaller.appspot.com/bug?extid=24458cef7d37351dd0c3
[...]
Reported-by: syzbot+24458cef7d37351dd0c3@syzkaller.appspotmail.com
[...]
===================================================== BUG: KMSAN: uninit-value in batadv_interface_tx+0x10cf/0x2450 net/batman-adv/soft-interface.c:264
This line is just comparing the eth_hdr(skb)->h_dest with the STP address (static const buffer).
Is there some situation when hsr would not initialize offset for eth_hdr() correctly or where h_dest is not initialized from a correctly initialized value? At least the comparisons with eth_hdr(skb)->h_source didn't cause this error.
Regarding my assupmtion: it seems like the hsr_xmit is only initializing the h_source in master mode. And there even more conditions (see hsr_addr_subst_dest) for initializing the h_dest in master mode.
Btw. the code in hsr which "stored this" was
if (skb_put_padto(skb, ETH_ZLEN + HSR_HLEN)) return;
[...]
batadv_interface_tx+0x10cf/0x2450 net/batman-adv/soft-interface.c:264 __netdev_start_xmit include/linux/netdevice.h:4447 [inline] netdev_start_xmit include/linux/netdevice.h:4461 [inline] xmit_one net/core/dev.c:3420 [inline] dev_hard_start_xmit+0x531/0xab0 net/core/dev.c:3436 __dev_queue_xmit+0x37de/0x4220 net/core/dev.c:4013 dev_queue_xmit+0x4b/0x60 net/core/dev.c:4046 hsr_xmit net/hsr/hsr_forward.c:228 [inline] hsr_forward_do net/hsr/hsr_forward.c:285 [inline] hsr_forward_skb+0x2614/0x30d0 net/hsr/hsr_forward.c:361 hsr_handle_frame+0x385/0x4b0 net/hsr/hsr_slave.c:43 __netif_receive_skb_core+0x21de/0x5840 net/core/dev.c:5051 __netif_receive_skb_one_core net/core/dev.c:5148 [inline] __netif_receive_skb net/core/dev.c:5264 [inline] process_backlog+0x936/0x1410 net/core/dev.c:6095 napi_poll net/core/dev.c:6532 [inline] net_rx_action+0x786/0x1ab0 net/core/dev.c:6600 __do_softirq+0x311/0x83d kernel/softirq.c:293 run_ksoftirqd+0x25/0x40 kernel/softirq.c:607 smpboot_thread_fn+0x493/0x980 kernel/smpboot.c:165 kthread+0x4b5/0x4f0 kernel/kthread.c:256 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:353
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310 kmsan_memcpy_memmove_metadata+0x272/0x2e0 mm/kmsan/kmsan.c:247 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:267 __msan_memcpy+0x43/0x50 mm/kmsan/kmsan_instr.c:116 pskb_expand_head+0x38b/0x1b00 net/core/skbuff.c:1637 __skb_pad+0x47f/0x900 net/core/skbuff.c:1805 __skb_put_padto include/linux/skbuff.h:3193 [inline] skb_put_padto include/linux/skbuff.h:3212 [inline] send_hsr_supervision_frame+0x122d/0x1500 net/hsr/hsr_device.c:310 hsr_announce+0x1e2/0x370 net/hsr/hsr_device.c:341 call_timer_fn+0x218/0x510 kernel/time/timer.c:1404 expire_timers kernel/time/timer.c:1449 [inline] __run_timers+0xcff/0x1210 kernel/time/timer.c:1773 run_timer_softirq+0x2d/0x50 kernel/time/timer.c:1786 __do_softirq+0x311/0x83d kernel/softirq.c:293
Kind regards, Sven