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BUG: KMSAN: kernel-infoleak in kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
CPU: 1 PID: 8756 Comm: syz-executor338 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
 kmsan_internal_check_memory+0x238/0x3d0 mm/kmsan/kmsan.c:423
 kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
 instrument_copy_to_user include/linux/instrumented.h:91 [inline]
 copyout lib/iov_iter.c:147 [inline]
 _copy_to_iter+0x626/0x2de0 lib/iov_iter.c:640
 copy_to_iter include/linux/uio.h:138 [inline]
 simple_copy_to_iter+0xf6/0x150 net/core/datagram.c:519
 __skb_datagram_iter+0x2d1/0x12b0 net/core/datagram.c:425
 skb_copy_datagram_iter+0x2a7/0x2c0 net/core/datagram.c:533
 skb_copy_datagram_msg include/linux/skbuff.h:3511 [inline]
 packet_recvmsg+0x74d/0x2020 net/packet/af_packet.c:3378
 sock_recvmsg_nosec net/socket.c:886 [inline]
 sock_recvmsg net/socket.c:904 [inline]
 __sys_recvfrom+0x69a/0xa10 net/socket.c:2052
 __do_sys_recvfrom net/socket.c:2070 [inline]
 __se_sys_recvfrom+0x111/0x130 net/socket.c:2066
 __x64_sys_recvfrom+0x6e/0x90 net/socket.c:2066
 do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x443ca9
Code: Bad RIP value.
RSP: 002b:00007ffdbfb30db8 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000443ca9
RDX: 00000000000000bd RSI: 0000000020000080 RDI: 0000000000000004
RBP: 00007ffdbfb30dd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000022ef3
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

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+0x3fd/0x1e30 net/core/skbuff.c:1636
 __skb_cow include/linux/skbuff.h:3145 [inline]
 skb_cow_head include/linux/skbuff.h:3179 [inline]
 batadv_skb_head_push+0x2cc/0x410 net/batman-adv/soft-interface.c:75
 batadv_send_skb_packet+0x1ed/0x970 net/batman-adv/send.c:86
 batadv_send_broadcast_skb+0x76/0x90 net/batman-adv/send.c:127
 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:393 [inline]
 batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:419 [inline]
 batadv_iv_send_outstanding_bat_ogm_packet+0xb2e/0xef0 net/batman-adv/bat_iv_ogm.c:1710
 process_one_work+0x1688/0x2140 kernel/workqueue.c:2269
 worker_thread+0x10bc/0x2730 kernel/workqueue.c:2415
 kthread+0x551/0x590 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:144
 kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:269 [inline]
 kmsan_alloc_page+0xc5/0x1a0 mm/kmsan/kmsan_shadow.c:293
 __alloc_pages_nodemask+0xdf0/0x1030 mm/page_alloc.c:4889
 __alloc_pages include/linux/gfp.h:509 [inline]
 __alloc_pages_node include/linux/gfp.h:522 [inline]
 alloc_pages_node include/linux/gfp.h:536 [inline]
 __page_frag_cache_refill mm/page_alloc.c:4964 [inline]
 page_frag_alloc+0x35b/0x880 mm/page_alloc.c:4994
 __napi_alloc_skb+0x1cf/0xb10 net/core/skbuff.c:519
 napi_alloc_skb include/linux/skbuff.h:2850 [inline]
 page_to_skb+0x135/0x1730 drivers/net/virtio_net.c:384
 receive_mergeable+0x107f/0x5ed0 drivers/net/virtio_net.c:944
 receive_buf+0x2f0/0x2c70 drivers/net/virtio_net.c:1054
 virtnet_receive drivers/net/virtio_net.c:1346 [inline]
 virtnet_poll+0xa51/0x1d10 drivers/net/virtio_net.c:1451
 napi_poll+0x43b/0xfd0 net/core/dev.c:6684
 net_rx_action+0x35c/0xd40 net/core/dev.c:6752
 __do_softirq+0x2ea/0x7f5 kernel/softirq.c:293

Bytes 52-53 of 146 are uninitialized
Memory access of size 146 starts at ffff888104532040
Data copied to user address 0000000020000080
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