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KASAN: use-after-free Read in __cfg8NUM_wpan_dev_from_attrs (2)

Status: fixed on 2020/11/16 12:12
Subsystems: wpan
[Documentation on labels]
Reported-by: syzbot+14e0e4960091ffae7cf7@syzkaller.appspotmail.com
Fix commit: bf64ff4c2aac genetlink: get rid of family->attrbuf
First crash: 1475d, last: 1474d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: fixed by (bisect log) :
commit bf64ff4c2aac65d680dc639a511c781cf6b6ec08
Author: Cong Wang <xiyou.wangcong@gmail.com>
Date: Sat Jun 27 07:12:24 2020 +0000

  genetlink: get rid of family->attrbuf

  
Discussions (1)
Title Replies (including bot) Last reply
KASAN: use-after-free Read in __cfg8NUM_wpan_dev_from_attrs (2) 1 (3) 2020/11/11 11:24
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in __cfg8NUM_wpan_dev_from_attrs wpan C done 3 1746d 1746d 15/27 fixed on 2019/12/13 00:31

Sample crash report:
netlink: 26 bytes leftover after parsing attributes in process `syz-executor982'.
==================================================================
BUG: KASAN: use-after-free in nla_len include/net/netlink.h:1135 [inline]
BUG: KASAN: use-after-free in nla_memcpy+0x9c/0xa0 lib/nlattr.c:724
Read of size 2 at addr ffff8880a0ca8414 by task syz-executor982/6816

CPU: 0 PID: 6816 Comm: syz-executor982 Not tainted 5.8.0-rc2-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+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 nla_len include/net/netlink.h:1135 [inline]
 nla_memcpy+0x9c/0xa0 lib/nlattr.c:724
 nla_get_u64 include/net/netlink.h:1606 [inline]
 __cfg802154_wpan_dev_from_attrs+0x3e0/0x510 net/ieee802154/nl802154.c:55
 nl802154_prepare_wpan_dev_dump.constprop.0+0xf9/0x490 net/ieee802154/nl802154.c:245
 nl802154_dump_llsec_dev+0xc0/0xb10 net/ieee802154/nl802154.c:1655
 genl_lock_dumpit+0x7f/0xb0 net/netlink/genetlink.c:575
 netlink_dump+0x4cd/0xf60 net/netlink/af_netlink.c:2245
 __netlink_dump_start+0x643/0x900 net/netlink/af_netlink.c:2353
 genl_family_rcv_msg_dumpit+0x2ac/0x310 net/netlink/genetlink.c:638
 genl_family_rcv_msg net/netlink/genetlink.c:733 [inline]
 genl_rcv_msg+0x797/0x9e0 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+0x533/0x7d0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 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: 0033:0x4413c9
Code: Bad RIP value.
RSP: 002b:00007fff5b30bca8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004413c9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000006cb018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000402140
R13: 00000000004021d0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 6815:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xae/0x550 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+0x94f/0xd90 net/netlink/af_netlink.c:1893
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 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 6815:
 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+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 skb_free_head net/core/skbuff.c:590 [inline]
 skb_release_data+0x6d9/0x910 net/core/skbuff.c:610
 skb_release_all net/core/skbuff.c:664 [inline]
 __kfree_skb net/core/skbuff.c:678 [inline]
 consume_skb net/core/skbuff.c:837 [inline]
 consume_skb+0xc2/0x160 net/core/skbuff.c:831
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x53b/0x7d0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 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 ffff8880a0ca8400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 20 bytes inside of
 512-byte region [ffff8880a0ca8400, ffff8880a0ca8600)
The buggy address belongs to the page:
page:ffffea0002832a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029e1288 ffffea00028ef888 ffff8880aa000a80
raw: 0000000000000000 ffff8880a0ca8000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a0ca8300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a0ca8380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a0ca8400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8880a0ca8480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a0ca8500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/07/04 21:15 net-next-old e44f65fd666c 51095195 .config console log report syz C ci-upstream-net-kasan-gce
2020/07/05 15:03 upstream 7cc2a8ea1048 51095195 .config console log report syz ci-upstream-kasan-gce-selinux-root
2020/07/05 01:29 upstream 7cc2a8ea1048 51095195 .config console log report syz ci-upstream-kasan-gce-root
2020/07/04 21:36 upstream 7cc2a8ea1048 51095195 .config console log report syz ci-upstream-kasan-gce-smack-root
2020/07/04 17:38 net-next-old e44f65fd666c 51095195 .config console log report ci-upstream-net-kasan-gce
* Struck through repros no longer work on HEAD.