syzbot


KASAN: use-after-free Read in __cfg8NUM_wpan_dev_from_attrs

Status: fixed on 2019/12/13 00:31
Reported-by: syzbot+9cb7edb2906ea1e83006@syzkaller.appspotmail.com
Fix commit: ab5b526da048 net: genetlink: always allocate separate attrs for dumpit ops
First crash: 1160d, last: 1160d

Cause bisection: introduced by (bisect log) :
commit 75cdbdd089003cd53560ff87b690ae911fa7df8e
Author: Jiri Pirko <jiri@mellanox.com>
Date: Sat Oct 5 18:04:37 2019 +0000

  net: ieee802154: have genetlink code to parse the attrs during dumpit

Crash: KASAN: use-after-free Read in __cfg8NUM_wpan_dev_from_attrs (log)
Repro: C syz .config
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 (2) C error done 5 887d 887d 17/24 fixed on 2020/11/16 12:12

Sample crash report:
netlink: 'syz-executor134': attribute type 6 has an invalid length.
==================================================================
BUG: KASAN: use-after-free in nla_memcpy+0xa2/0xb0 lib/nlattr.c:572
Read of size 2 at addr ffff8880a74fba94 by task syz-executor134/8714

CPU: 1 PID: 8714 Comm: syz-executor134 Not tainted 5.4.0-rc1+ #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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/generic_report.c:130
 nla_memcpy+0xa2/0xb0 lib/nlattr.c:572
 nla_get_u64 include/net/netlink.h:1539 [inline]
 __cfg802154_wpan_dev_from_attrs+0x41b/0x550 net/ieee802154/nl802154.c:55
 nl802154_prepare_wpan_dev_dump.isra.0.constprop.0+0xf7/0x4b0 net/ieee802154/nl802154.c:245
 nl802154_dump_llsec_seclevel+0xb9/0xae0 net/ieee802154/nl802154.c:1985
 genl_lock_dumpit+0x86/0xc0 net/netlink/genetlink.c:529
 netlink_dump+0x558/0xfb0 net/netlink/af_netlink.c:2244
 __netlink_dump_start+0x5b1/0x7d0 net/netlink/af_netlink.c:2352
 genl_family_rcv_msg_dumpit net/netlink/genetlink.c:614 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:710 [inline]
 genl_rcv_msg+0xc9b/0x1000 net/netlink/genetlink.c:730
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
 genl_rcv+0x29/0x40 net/netlink/genetlink.c:741
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x8a5/0xd60 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:657
 ___sys_sendmsg+0x803/0x920 net/socket.c:2311
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2356
 __do_sys_sendmsg net/socket.c:2365 [inline]
 __se_sys_sendmsg net/socket.c:2363 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2363
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441399
Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe350885d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441399
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000006cb018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000402110
R13: 00000000004021a0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 8716:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 __do_kmalloc_node mm/slab.c:3615 [inline]
 __kmalloc_node_track_caller+0x4e/0x70 mm/slab.c:3629
 __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:141
 __alloc_skb+0x10b/0x5e0 net/core/skbuff.c:209
 alloc_skb include/linux/skbuff.h:1049 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1174 [inline]
 netlink_sendmsg+0x972/0xd60 net/netlink/af_netlink.c:1892
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:657
 ___sys_sendmsg+0x803/0x920 net/socket.c:2311
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2356
 __do_sys_sendmsg net/socket.c:2365 [inline]
 __se_sys_sendmsg net/socket.c:2363 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2363
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8716:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3756
 skb_free_head+0x93/0xb0 net/core/skbuff.c:591
 skb_release_data+0x42d/0x7c0 net/core/skbuff.c:611
 skb_release_all+0x4d/0x60 net/core/skbuff.c:665
 __kfree_skb net/core/skbuff.c:679 [inline]
 consume_skb net/core/skbuff.c:838 [inline]
 consume_skb+0xfb/0x3b0 net/core/skbuff.c:832
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x539/0x710 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x8a5/0xd60 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:657
 ___sys_sendmsg+0x803/0x920 net/socket.c:2311
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2356
 __do_sys_sendmsg net/socket.c:2365 [inline]
 __se_sys_sendmsg net/socket.c:2363 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2363
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a74fba80
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 20 bytes inside of
 512-byte region [ffff8880a74fba80, ffff8880a74fbc80)
The buggy address belongs to the page:
page:ffffea00029d3ec0 refcount:1 mapcount:0 mapping:ffff8880aa400a80 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000232e1c8 ffffea00028722c8 ffff8880aa400a80
raw: 0000000000000000 ffff8880a74fb080 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a74fb980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a74fba00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a74fba80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8880a74fbb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a74fbb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-net-kasan-gce 2019/10/06 23:28 net-next 056ddc38e941 f3f7d9c8 .config log report syz C
ci-upstream-net-kasan-gce 2019/10/06 22:38 net-next 056ddc38e941 f3f7d9c8 .config log report
ci-upstream-net-kasan-gce 2019/10/06 22:32 net-next 056ddc38e941 f3f7d9c8 .config log report
* Struck through repros no longer work on HEAD.