Subject: KMSAN: uninit-value in __tipc_nl_compat_dumpit (3)

From: syzbot <[email-masked]>
Date: Mon, 13 Jul 2020 15:05:20 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    f0d5ec90 kmsan: apply __no_sanitize_memory to dotraplinkag..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1206d73d100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=86e4f8af239686c6
dashboard link: https://syzkaller.appspot.com/bug?extid=0e7181deafa7e0b79923
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15a6948f100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=144e2047100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]

=====================================================
BUG: KMSAN: uninit-value in __nlmsg_parse include/net/netlink.h:661 [inline]
BUG: KMSAN: uninit-value in nlmsg_parse_deprecated include/net/netlink.h:706 [inline]
BUG: KMSAN: uninit-value in __tipc_nl_compat_dumpit+0x583/0x1290 net/tipc/netlink_compat.c:215
CPU: 0 PID: 8825 Comm: syz-executor230 Not tainted 5.7.0-rc4-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+0x1c9/0x220 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
 __nlmsg_parse include/net/netlink.h:661 [inline]
 nlmsg_parse_deprecated include/net/netlink.h:706 [inline]
 __tipc_nl_compat_dumpit+0x583/0x1290 net/tipc/netlink_compat.c:215
 tipc_nl_compat_dumpit+0x761/0x910 net/tipc/netlink_compat.c:308
 tipc_nl_compat_handle net/tipc/netlink_compat.c:1272 [inline]
 tipc_nl_compat_recv+0x1382/0x2940 net/tipc/netlink_compat.c:1311
 genl_family_rcv_msg_doit net/netlink/genetlink.c:673 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:718 [inline]
 genl_rcv_msg+0x20dc/0x2480 net/netlink/genetlink.c:735
 netlink_rcv_skb+0x451/0x650 net/netlink/af_netlink.c:2469
 genl_rcv+0x63/0x80 net/netlink/genetlink.c:746
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2362
 ___sys_sendmsg net/socket.c:2416 [inline]
 __sys_sendmsg+0x623/0x750 net/socket.c:2449
 __do_sys_sendmsg net/socket.c:2458 [inline]
 __se_sys_sendmsg+0x97/0xb0 net/socket.c:2456
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2456
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x444219
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 1b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffded8626b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000444219
RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00000000006ce018 R08: 00000000004002e0 R09: 00000000004002e0
R10: 0000000000001900 R11: 0000000000000246 R12: 0000000000401ec0
R13: 0000000000401f50 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:80
 slab_alloc_node mm/slub.c:2802 [inline]
 __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4436
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1083 [inline]
 nlmsg_new include/net/netlink.h:888 [inline]
 tipc_nl_compat_dumpit+0x6e4/0x910 net/tipc/netlink_compat.c:301
 tipc_nl_compat_handle net/tipc/netlink_compat.c:1272 [inline]
 tipc_nl_compat_recv+0x1382/0x2940 net/tipc/netlink_compat.c:1311
 genl_family_rcv_msg_doit net/netlink/genetlink.c:673 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:718 [inline]
 genl_rcv_msg+0x20dc/0x2480 net/netlink/genetlink.c:735
 netlink_rcv_skb+0x451/0x650 net/netlink/af_netlink.c:2469
 genl_rcv+0x63/0x80 net/netlink/genetlink.c:746
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2362
 ___sys_sendmsg net/socket.c:2416 [inline]
 __sys_sendmsg+0x623/0x750 net/socket.c:2449
 __do_sys_sendmsg net/socket.c:2458 [inline]
 __se_sys_sendmsg+0x97/0xb0 net/socket.c:2456
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2456
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
=====================================================

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