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BUG: KMSAN: uninit-value in udp_csum include/net/udp.h:141 [inline]
BUG: KMSAN: uninit-value in udp_v6_send_skb+0x1925/0x1ca0 net/ipv6/udp.c:1253
 udp_csum include/net/udp.h:141 [inline]
 udp_v6_send_skb+0x1925/0x1ca0 net/ipv6/udp.c:1253
 udp_v6_push_pending_frames+0x1eb/0x290 net/ipv6/udp.c:1289
 udpv6_sendmsg+0x119e/0x4440 net/ipv6/udp.c:1582
 inet6_sendmsg+0x101/0x180 net/ipv6/af_inet6.c:653
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 ____sys_sendmsg+0xabc/0xe90 net/socket.c:2482
 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2536
 __sys_sendmmsg+0x40d/0xa40 net/socket.c:2622
 __do_sys_sendmmsg net/socket.c:2651 [inline]
 __se_sys_sendmmsg net/socket.c:2648 [inline]
 __x64_sys_sendmmsg+0xb8/0x120 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was stored to memory at:
 __ip6_append_data+0x5b51/0x6b80 net/ipv6/ip6_output.c:1711
 ip6_append_data+0x437/0x5b0 net/ipv6/ip6_output.c:1852
 udpv6_sendmsg+0xf7a/0x4440 net/ipv6/udp.c:1576
 inet6_sendmsg+0x101/0x180 net/ipv6/af_inet6.c:653
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 ____sys_sendmsg+0xabc/0xe90 net/socket.c:2482
 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2536
 __sys_sendmmsg+0x40d/0xa40 net/socket.c:2622
 __do_sys_sendmmsg net/socket.c:2651 [inline]
 __se_sys_sendmmsg net/socket.c:2648 [inline]
 __x64_sys_sendmmsg+0xb8/0x120 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was stored to memory at:
 csum_partial_copy_nocheck include/net/checksum.h:51 [inline]
 skb_copy_and_csum_bits+0x128/0x1270 net/core/skbuff.c:2993
 __ip6_append_data+0x5613/0x6b80 net/ipv6/ip6_output.c:1708
 ip6_append_data+0x437/0x5b0 net/ipv6/ip6_output.c:1852
 udpv6_sendmsg+0xf7a/0x4440 net/ipv6/udp.c:1576
 inet6_sendmsg+0x101/0x180 net/ipv6/af_inet6.c:653
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 ____sys_sendmsg+0xabc/0xe90 net/socket.c:2482
 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2536
 __sys_sendmmsg+0x40d/0xa40 net/socket.c:2622
 __do_sys_sendmmsg net/socket.c:2651 [inline]
 __se_sys_sendmmsg net/socket.c:2648 [inline]
 __x64_sys_sendmmsg+0xb8/0x120 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:732 [inline]
 slab_alloc_node mm/slub.c:3258 [inline]
 __kmalloc_node_track_caller+0x814/0x1250 mm/slub.c:4970
 kmalloc_reserve net/core/skbuff.c:362 [inline]
 __alloc_skb+0x346/0xcf0 net/core/skbuff.c:434
 alloc_skb include/linux/skbuff.h:1257 [inline]
 alloc_skb_with_frags+0xb9/0xba0 net/core/skbuff.c:6021
 sock_alloc_send_pskb+0xaa8/0xc30 net/core/sock.c:2665
 sock_alloc_send_skb include/net/sock.h:1866 [inline]
 __ip6_append_data+0x509c/0x6b80 net/ipv6/ip6_output.c:1676
 ip6_append_data+0x437/0x5b0 net/ipv6/ip6_output.c:1852
 udpv6_sendmsg+0xf7a/0x4440 net/ipv6/udp.c:1576
 inet6_sendmsg+0x101/0x180 net/ipv6/af_inet6.c:653
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 __sys_sendto+0x7f2/0xa60 net/socket.c:2117
 __do_sys_sendto net/socket.c:2129 [inline]
 __se_sys_sendto net/socket.c:2125 [inline]
 __x64_sys_sendto+0x121/0x1c0 net/socket.c:2125
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

CPU: 1 PID: 25645 Comm: syz-executor.5 Not tainted 6.0.0-rc5-syzkaller-48543-g968c2729e576 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
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