syzbot has found a reproducer for the following issue on: HEAD commit: 14525656 compiler.h: reinstate missing KMSAN_INIT git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=16a7c827100000 kernel config: https://syzkaller.appspot.com/x/.config?x=c534a9fad6323722 dashboard link: https://syzkaller.appspot.com/bug?extid=721b564cd88ebb710182 compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=115be9d7100000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15b9425f100000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+721b564cd88ebb710182@xxxxxxxxxxxxxxxxxxxxxxxxx ===================================================== BUG: KMSAN: uninit-value in __skb_checksum_complete+0x37f/0x540 net/core/skbuff.c:2850 CPU: 1 PID: 8457 Comm: syz-executor769 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+0x1df/0x240 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215 __skb_checksum_complete+0x37f/0x540 net/core/skbuff.c:2850 nf_ip_checksum+0x53b/0x740 net/netfilter/utils.c:36 nf_nat_icmp_reply_translation+0x2ba/0x980 net/netfilter/nf_nat_proto.c:578 nf_nat_ipv4_fn net/netfilter/nf_nat_proto.c:637 [inline] nf_nat_ipv4_local_fn+0x215/0x830 net/netfilter/nf_nat_proto.c:708 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline] nf_hook_slow+0x16e/0x400 net/netfilter/core.c:512 nf_hook include/linux/netfilter.h:262 [inline] __ip_local_out+0x69b/0x800 net/ipv4/ip_output.c:114 ip_local_out net/ipv4/ip_output.c:123 [inline] ip_send_skb net/ipv4/ip_output.c:1560 [inline] ip_push_pending_frames+0x16f/0x460 net/ipv4/ip_output.c:1580 icmp_push_reply+0x660/0x710 net/ipv4/icmp.c:390 __icmp_send+0x23ca/0x3150 net/ipv4/icmp.c:740 icmp_send include/net/icmp.h:43 [inline] ip_fragment+0x39f/0x400 net/ipv4/ip_output.c:579 __ip_finish_output+0xd34/0xd80 net/ipv4/ip_output.c:304 ip_finish_output+0x166/0x410 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_output+0x593/0x680 net/ipv4/ip_output.c:430 dst_output include/net/dst.h:443 [inline] ip_local_out net/ipv4/ip_output.c:125 [inline] __ip_queue_xmit+0x1b5c/0x21a0 net/ipv4/ip_output.c:530 ip_queue_xmit include/net/ip.h:237 [inline] l2tp_ip_sendmsg+0x1477/0x1870 net/l2tp/l2tp_ip.c:508 inet_sendmsg+0x2d8/0x2e0 net/ipv4/af_inet.c:814 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg net/socket.c:672 [inline] kernel_sendmsg+0x384/0x440 net/socket.c:692 sock_no_sendpage+0x235/0x300 net/core/sock.c:2853 kernel_sendpage net/socket.c:3642 [inline] sock_sendpage+0x1e1/0x2c0 net/socket.c:945 pipe_to_sendpage+0x38c/0x4c0 fs/splice.c:448 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x565/0xf00 fs/splice.c:626 splice_from_pipe fs/splice.c:661 [inline] generic_splice_sendpage+0x1d5/0x2d0 fs/splice.c:834 do_splice_from fs/splice.c:846 [inline] direct_splice_actor+0x1fd/0x580 fs/splice.c:1016 splice_direct_to_actor+0x6b2/0xf50 fs/splice.c:971 do_splice_direct+0x342/0x580 fs/splice.c:1059 do_sendfile+0x101b/0x1d40 fs/read_write.c:1540 __do_sys_sendfile64 fs/read_write.c:1601 [inline] __se_sys_sendfile64+0x2bb/0x360 fs/read_write.c:1587 __x64_sys_sendfile64+0x56/0x70 fs/read_write.c:1587 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x440409 Code: Bad RIP value. RSP: 002b:00007ffe9c5d76d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440409 RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000003 RBP: 00000000006cb018 R08: 0000000000000014 R09: 65732f636f72702f R10: 0800000080004103 R11: 0000000000000246 R12: 0000000000401c70 R13: 0000000000401d00 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 csum_partial_copy+0xae/0x100 lib/checksum.c:154 skb_copy_and_csum_bits+0x227/0x1130 net/core/skbuff.c:2737 icmp_glue_bits+0x166/0x380 net/ipv4/icmp.c:353 __ip_append_data+0x47c4/0x5630 net/ipv4/ip_output.c:1131 ip_append_data+0x328/0x480 net/ipv4/ip_output.c:1315 icmp_push_reply+0x206/0x710 net/ipv4/icmp.c:371 __icmp_send+0x23ca/0x3150 net/ipv4/icmp.c:740 icmp_send include/net/icmp.h:43 [inline] ip_fragment+0x39f/0x400 net/ipv4/ip_output.c:579 __ip_finish_output+0xd34/0xd80 net/ipv4/ip_output.c:304 ip_finish_output+0x166/0x410 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_output+0x593/0x680 net/ipv4/ip_output.c:430 dst_output include/net/dst.h:443 [inline] ip_local_out net/ipv4/ip_output.c:125 [inline] __ip_queue_xmit+0x1b5c/0x21a0 net/ipv4/ip_output.c:530 ip_queue_xmit include/net/ip.h:237 [inline] l2tp_ip_sendmsg+0x1477/0x1870 net/l2tp/l2tp_ip.c:508 inet_sendmsg+0x2d8/0x2e0 net/ipv4/af_inet.c:814 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg net/socket.c:672 [inline] kernel_sendmsg+0x384/0x440 net/socket.c:692 sock_no_sendpage+0x235/0x300 net/core/sock.c:2853 kernel_sendpage net/socket.c:3642 [inline] sock_sendpage+0x1e1/0x2c0 net/socket.c:945 pipe_to_sendpage+0x38c/0x4c0 fs/splice.c:448 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x565/0xf00 fs/splice.c:626 splice_from_pipe fs/splice.c:661 [inline] generic_splice_sendpage+0x1d5/0x2d0 fs/splice.c:834 do_splice_from fs/splice.c:846 [inline] direct_splice_actor+0x1fd/0x580 fs/splice.c:1016 splice_direct_to_actor+0x6b2/0xf50 fs/splice.c:971 do_splice_direct+0x342/0x580 fs/splice.c:1059 do_sendfile+0x101b/0x1d40 fs/read_write.c:1540 __do_sys_sendfile64 fs/read_write.c:1601 [inline] __se_sys_sendfile64+0x2bb/0x360 fs/read_write.c:1587 __x64_sys_sendfile64+0x56/0x70 fs/read_write.c:1587 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 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 _copy_from_iter_full+0xbfe/0x13b0 lib/iov_iter.c:793 copy_from_iter_full include/linux/uio.h:156 [inline] memcpy_from_msg include/linux/skbuff.h:3566 [inline] l2tp_ip_sendmsg+0x6a5/0x1870 net/l2tp/l2tp_ip.c:462 inet_sendmsg+0x2d8/0x2e0 net/ipv4/af_inet.c:814 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg net/socket.c:672 [inline] kernel_sendmsg+0x384/0x440 net/socket.c:692 sock_no_sendpage+0x235/0x300 net/core/sock.c:2853 kernel_sendpage net/socket.c:3642 [inline] sock_sendpage+0x1e1/0x2c0 net/socket.c:945 pipe_to_sendpage+0x38c/0x4c0 fs/splice.c:448 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x565/0xf00 fs/splice.c:626 splice_from_pipe fs/splice.c:661 [inline] generic_splice_sendpage+0x1d5/0x2d0 fs/splice.c:834 do_splice_from fs/splice.c:846 [inline] direct_splice_actor+0x1fd/0x580 fs/splice.c:1016 splice_direct_to_actor+0x6b2/0xf50 fs/splice.c:971 do_splice_direct+0x342/0x580 fs/splice.c:1059 do_sendfile+0x101b/0x1d40 fs/read_write.c:1540 __do_sys_sendfile64 fs/read_write.c:1601 [inline] __se_sys_sendfile64+0x2bb/0x360 fs/read_write.c:1587 __x64_sys_sendfile64+0x56/0x70 fs/read_write.c:1587 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 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+0xb9/0x180 mm/kmsan/kmsan_shadow.c:293 __alloc_pages_nodemask+0x56a2/0x5dc0 mm/page_alloc.c:4889 alloc_pages_current+0x672/0x990 mm/mempolicy.c:2292 alloc_pages include/linux/gfp.h:545 [inline] push_pipe+0x605/0xb70 lib/iov_iter.c:537 __pipe_get_pages lib/iov_iter.c:1278 [inline] pipe_get_pages_alloc lib/iov_iter.c:1385 [inline] iov_iter_get_pages_alloc+0x18a9/0x21c0 lib/iov_iter.c:1403 default_file_splice_read fs/splice.c:385 [inline] do_splice_to+0x4fc/0x14f0 fs/splice.c:871 splice_direct_to_actor+0x45c/0xf50 fs/splice.c:950 do_splice_direct+0x342/0x580 fs/splice.c:1059 do_sendfile+0x101b/0x1d40 fs/read_write.c:1540 __do_sys_sendfile64 fs/read_write.c:1601 [inline] __se_sys_sendfile64+0x2bb/0x360 fs/read_write.c:1587 __x64_sys_sendfile64+0x56/0x70 fs/read_write.c:1587 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 =====================================================
