KMSAN: uninit-value in tipc_nl_compat_link_set (3)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    c530a275 kmsan: call vmap hooks from vmalloc and ioremap f..
git tree:       kmsan
console output: https://syzkaller.appspot.com/x/log.txt?x=13bd4733200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
dashboard link: https://syzkaller.appspot.com/bug?extid=de00a87b8644a582ae79
compiler:       clang version 8.0.0 (trunk 350509)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12c534d7200000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10f9e733200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+de00a87b8644a582ae79@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KMSAN: uninit-value in memchr+0xce/0x110 lib/string.c:961
CPU: 1 PID: 10538 Comm: syz-executor101 Not tainted 5.0.0+ #12
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+0x12e/0x2a0 mm/kmsan/kmsan.c:600
 __msan_warning+0x82/0xf0 mm/kmsan/kmsan_instr.c:313
 memchr+0xce/0x110 lib/string.c:961
 string_is_valid net/tipc/netlink_compat.c:176 [inline]
 tipc_nl_compat_link_set+0x121/0x1550 net/tipc/netlink_compat.c:770
 __tipc_nl_compat_doit net/tipc/netlink_compat.c:321 [inline]
 tipc_nl_compat_doit+0x3aa/0xaf0 net/tipc/netlink_compat.c:354
 tipc_nl_compat_handle net/tipc/netlink_compat.c:1162 [inline]
 tipc_nl_compat_recv+0x1ae7/0x2750 net/tipc/netlink_compat.c:1265
 genl_family_rcv_msg net/netlink/genetlink.c:601 [inline]
 genl_rcv_msg+0x185f/0x1a60 net/netlink/genetlink.c:626
 netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2477
 genl_rcv+0x63/0x80 net/netlink/genetlink.c:637
 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
 netlink_unicast+0xf3e/0x1020 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0x127f/0x1300 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg net/socket.c:632 [inline]
 ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
 __sys_sendmsg net/socket.c:2153 [inline]
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x440259
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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcb435a248 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440259
RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401ae0
R13: 0000000000401b70 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
 kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:159
 kmsan_kmalloc+0xa6/0x130 mm/kmsan/kmsan_hooks.c:176
 kmsan_slab_alloc+0xe/0x10 mm/kmsan/kmsan_hooks.c:185
 slab_post_alloc_hook mm/slab.h:445 [inline]
 slab_alloc_node mm/slub.c:2773 [inline]
 __kmalloc_node_track_caller+0xe9e/0xff0 mm/slub.c:4398
 __kmalloc_reserve net/core/skbuff.c:140 [inline]
 __alloc_skb+0x309/0xa20 net/core/skbuff.c:208
 alloc_skb include/linux/skbuff.h:1012 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1182 [inline]
 netlink_sendmsg+0xb82/0x1300 net/netlink/af_netlink.c:1892
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg net/socket.c:632 [inline]
 ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
 __sys_sendmsg net/socket.c:2153 [inline]
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
==================================================================


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