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BUG: KMSAN: uninit-value in br_nf_forward_arp+0x9d8/0xed0 net/bridge/br_netfilter_hooks.c:636
CPU: 0 PID: 2344 Comm: syz-executor.2 Not tainted 5.1.0-rc2+ #24
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+0x173/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:619
 __msan_warning+0x7a/0xf0 mm/kmsan/kmsan_instr.c:310
bridge0: received packet on syz_tun with own address as source address (addr:aa:aa:aa:aa:aa:aa, vlan:0)
 br_nf_forward_arp+0x9d8/0xed0 net/bridge/br_netfilter_hooks.c:636
 nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline]
 nf_hook_slow+0x176/0x3d0 net/netfilter/core.c:511
 nf_hook include/linux/netfilter.h:244 [inline]
 NF_HOOK include/linux/netfilter.h:287 [inline]
 __br_forward+0x7a7/0xe10 net/bridge/br_forward.c:113
 deliver_clone net/bridge/br_forward.c:129 [inline]
 maybe_deliver net/bridge/br_forward.c:184 [inline]
 br_flood+0xc65/0x10b0 net/bridge/br_forward.c:226
 br_handle_frame_finish+0x19e4/0x1bc0 net/bridge/br_input.c:169
 NF_HOOK include/linux/netfilter.h:289 [inline]
 br_handle_frame+0xf0c/0x2020 net/bridge/br_input.c:305
 __netif_receive_skb_core+0x1edd/0x5030 net/core/dev.c:4902
 __netif_receive_skb_one_core net/core/dev.c:4971 [inline]
 __netif_receive_skb net/core/dev.c:5083 [inline]
 netif_receive_skb_internal+0x4d5/0x9a0 net/core/dev.c:5186
bridge0: received packet on syz_tun with own address as source address (addr:aa:aa:aa:aa:aa:aa, vlan:0)
 netif_receive_skb+0x256/0x480 net/core/dev.c:5261
 tun_rx_batched include/linux/skbuff.h:4174 [inline]
 tun_get_user+0x6914/0x6e00 drivers/net/tun.c:1991
 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2019
 do_iter_readv_writev+0x9b3/0xbd0 include/linux/fs.h:1857
 do_iter_write+0x304/0xdc0 fs/read_write.c:956
 vfs_writev fs/read_write.c:1001 [inline]
 do_writev+0x397/0x840 fs/read_write.c:1036
 __do_sys_writev fs/read_write.c:1109 [inline]
 __se_sys_writev+0x9b/0xb0 fs/read_write.c:1106
 __x64_sys_writev+0x4a/0x70 fs/read_write.c:1106
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x458171
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 e4 b9 fb ff c3 48 83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f72e2c04ba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000000010 RCX: 0000000000458171
RDX: 0000000000000001 RSI: 00007f72e2c04c00 RDI: 00000000000000f0
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f72e2c056d4
R13: 00000000004c693a R14: 00000000004dc230 R15: 00000000ffffffff

Uninit was created at:
 kmsan_save_stack_with_flags+0x7a/0x130 mm/kmsan/kmsan.c:205
 kmsan_internal_alloc_meta_for_pages+0x112/0x500 mm/kmsan/kmsan_hooks.c:99
 kmsan_alloc_page+0x7e/0x100 mm/kmsan/kmsan_hooks.c:243
 __alloc_pages_nodemask+0x12fb/0x5e90 mm/page_alloc.c:4644
 alloc_pages_current+0x6a4/0x9c0 mm/mempolicy.c:2106
 alloc_pages include/linux/gfp.h:511 [inline]
 skb_page_frag_refill+0x3b5/0x5b0 net/core/sock.c:2350
 tun_build_skb drivers/net/tun.c:1684 [inline]
 tun_get_user+0x1d62/0x6e00 drivers/net/tun.c:1827
 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2019
 do_iter_readv_writev+0x9b3/0xbd0 include/linux/fs.h:1857
 do_iter_write+0x304/0xdc0 fs/read_write.c:956
 vfs_writev fs/read_write.c:1001 [inline]
 do_writev+0x397/0x840 fs/read_write.c:1036
 __do_sys_writev fs/read_write.c:1109 [inline]
 __se_sys_writev+0x9b/0xb0 fs/read_write.c:1106
 __x64_sys_writev+0x4a/0x70 fs/read_write.c:1106
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
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