syz_tun: entered allmulticast mode
=====================================================
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline]
BUG: KMSAN: kernel-infoleak in iterate_iovec include/linux/iov_iter.h:52 [inline]
BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:328 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x4f3/0x32f0 lib/iov_iter.c:185
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 copy_to_user_iter lib/iov_iter.c:24 [inline]
 iterate_iovec include/linux/iov_iter.h:52 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
 iterate_and_advance include/linux/iov_iter.h:328 [inline]
 _copy_to_iter+0x4f3/0x32f0 lib/iov_iter.c:185
 copy_to_iter include/linux/uio.h:220 [inline]
 simple_copy_to_iter net/core/datagram.c:524 [inline]
 __skb_datagram_iter+0x18f/0x1250 net/core/datagram.c:401
 skb_copy_datagram_iter+0x5b/0x1e0 net/core/datagram.c:538
 skb_copy_datagram_msg include/linux/skbuff.h:4128 [inline]
 raw_recvmsg+0x2c8/0xab0 net/ipv4/raw.c:766
 inet_recvmsg+0x340/0x690 net/ipv4/af_inet.c:883
 sock_recvmsg_nosec net/socket.c:1017 [inline]
 sock_recvmsg+0x23c/0x390 net/socket.c:1039
 ____sys_recvmsg+0x193/0x610 net/socket.c:2786
 ___sys_recvmsg+0x20b/0x850 net/socket.c:2828
 do_recvmmsg+0x40e/0xdf0 net/socket.c:2923
 __sys_recvmmsg net/socket.c:2999 [inline]
 __do_sys_recvmmsg net/socket.c:3020 [inline]
 __se_sys_recvmmsg net/socket.c:3013 [inline]
 __x64_sys_recvmmsg+0x206/0x500 net/socket.c:3013
 x64_sys_call+0x220d/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x1b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4167 [inline]
 slab_alloc_node mm/slub.c:4210 [inline]
 kmem_cache_alloc_node_noprof+0x818/0xf00 mm/slub.c:4262
 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:577
 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1340 [inline]
 ipmr_cache_report+0x410/0x2200 net/ipv4/ipmr.c:1062
 ipmr_cache_unresolved+0x53d/0xd30 net/ipv4/ipmr.c:1162
 ip_mr_input+0xe78/0xfb0 net/ipv4/ipmr.c:2208
 dst_input include/net/dst.h:469 [inline]
 ip_rcv_finish+0x54d/0x570 net/ipv4/ip_input.c:447
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ip_rcv+0xcb/0x380 net/ipv4/ip_input.c:567
 __netif_receive_skb_one_core net/core/dev.c:5887 [inline]
 __netif_receive_skb+0x312/0xac0 net/core/dev.c:6000
 netif_receive_skb_internal net/core/dev.c:6086 [inline]
 netif_receive_skb+0x57/0x630 net/core/dev.c:6145
 tun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485
 tun_get_user+0x52a7/0x6a80 drivers/net/tun.c:1938
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1984
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0xb31/0x1560 fs/read_write.c:684
 ksys_write fs/read_write.c:736 [inline]
 __do_sys_write fs/read_write.c:747 [inline]
 __se_sys_write fs/read_write.c:744 [inline]
 __x64_sys_write+0x1fb/0x4d0 fs/read_write.c:744
 x64_sys_call+0x38c3/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x1b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Bytes 26-31 of 32 are uninitialized
Memory access of size 32 starts at ffff888118fe6100
Data copied to user address 0000200000000280

CPU: 1 UID: 0 PID: 8576 Comm: syz.4.464 Not tainted 6.15.0-rc3-syzkaller-00094-g02ddfb981de8 #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
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