KASAN: use-after-free Read in tipc_udp_nl_dump_remoteip (2)

KASAN: use-after-free Read in tipc_udp_nl_dump_remoteip (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    67c20de3 net: Add MODULE_DESCRIPTION entries to network mo..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=13ff86a5100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=45c80de7244166e1
dashboard link: https://syzkaller.appspot.com/bug?extid=3039ddf6d7b13daf3787
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1126c695100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=122afe35100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3039ddf6d7b13daf3787@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in nla_parse_nested_deprecated include/net/netlink.h:1218 [inline]
BUG: KASAN: use-after-free in tipc_udp_nl_dump_remoteip+0xb92/0xba0 net/tipc/udp_media.c:467
Read of size 2 at addr ffff8880a7da0c14 by task syz-executor132/7030

CPU: 0 PID: 7030 Comm: syz-executor132 Not tainted 5.8.0-rc1-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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 nla_parse_nested_deprecated include/net/netlink.h:1218 [inline]
 tipc_udp_nl_dump_remoteip+0xb92/0xba0 net/tipc/udp_media.c:467
 genl_lock_dumpit+0x7f/0xb0 net/netlink/genetlink.c:575
 netlink_dump+0x50b/0xe70 net/netlink/af_netlink.c:2245
 __netlink_dump_start+0x63f/0x910 net/netlink/af_netlink.c:2353
 genl_family_rcv_msg_dumpit.isra.0+0x296/0x300 net/netlink/genetlink.c:638
 genl_family_rcv_msg net/netlink/genetlink.c:733 [inline]
 genl_rcv_msg+0x781/0x9c0 net/netlink/genetlink.c:753
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2469
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:764
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e6/0x810 net/socket.c:2352
 ___sys_sendmsg+0x100/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4452c9
Code: Bad RIP value.
RSP: 002b:00007ffd2abff858 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004452c9
RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003
RBP: 000000000000f7f6 R08: 0000000000000000 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402460
R13: 00000000004024f0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 7032:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc mm/kasan/common.c:494 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467
 __kmalloc_reserve.isra.0+0x39/0xe0 net/core/skbuff.c:142
 __alloc_skb+0xef/0x5a0 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1083 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline]
 netlink_sendmsg+0x97b/0xe10 net/netlink/af_netlink.c:1893
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e6/0x810 net/socket.c:2352
 ___sys_sendmsg+0x100/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 7032:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 skb_free_head+0x8b/0xa0 net/core/skbuff.c:590
 skb_release_data+0x617/0x8a0 net/core/skbuff.c:610
 skb_release_all+0x46/0x60 net/core/skbuff.c:664
 __kfree_skb net/core/skbuff.c:678 [inline]
 consume_skb net/core/skbuff.c:837 [inline]
 consume_skb+0xf3/0x3f0 net/core/skbuff.c:831
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x53f/0x740 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e6/0x810 net/socket.c:2352
 ___sys_sendmsg+0x100/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880a7da0c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 20 bytes inside of
 512-byte region [ffff8880a7da0c00, ffff8880a7da0e00)
The buggy address belongs to the page:
page:ffffea00029f6800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000261b188 ffffea0002884808 ffff8880aa000a80
raw: 0000000000000000 ffff8880a7da0000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a7da0b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a7da0b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a7da0c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8880a7da0c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a7da0d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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