BUG: unable to handle kernel paging request in dummy_set_vf_trust

Status: fixed on 2019/12/05 10:31
Fix commit: 9ed49fc95f37 net: rtnetlink: prevent underflows in do_setvfinfo()
First crash: 1671d, last: 1638d
Fix bisection: fixed by (bisect log) :
commit 9ed49fc95f37a457d940324c033c20d85cefb930
Author: Dan Carpenter <>
Date: Wed Nov 20 12:34:38 2019 +0000

  net: rtnetlink: prevent underflows in do_setvfinfo()


Sample crash report:
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
audit: type=1400 audit(1564788260.663:36): avc:  denied  { map } for  pid=7136 comm="syz-executor987" path="/root/syz-executor987619628" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
BUG: unable to handle kernel paging request at fffffbfffd600002
IP: dummy_set_vf_trust+0x68/0xb0 drivers/net/dummy.c:243
PGD 21ffed067 P4D 21ffed067 PUD 21ffec067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7136 Comm: syz-executor987 Not tainted 4.14.135 #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888081126500 task.stack: ffff888096ef0000
RIP: 0010:dummy_set_vf_trust+0x68/0xb0 drivers/net/dummy.c:243
RSP: 0018:ffff888096ef72b0 EFLAGS: 00010a02
RAX: dffffc0000000000 RBX: ffffffffeb000000 RCX: 0000000000000000
RDX: 1ffffffffd600002 RSI: 00000000ff200000 RDI: ffffffffeb000012
RBP: ffff888096ef72c8 R08: 1ffff11012ddee99 R09: ffff888096ef74c8
R10: ffffed1012ddeea5 R11: ffff888096ef752f R12: ffff8880a1a16a00
R13: 0000000000000001 R14: ffff888096ef7610 R15: ffff88809764f028
FS:  000000000153d880(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfffd600002 CR3: 0000000097a3f000 CR4: 00000000001406f0
Call Trace:
 do_setvfinfo net/core/rtnetlink.c:1889 [inline]
 do_setlink+0x1ac5/0x2d50 net/core/rtnetlink.c:2135
 rtnl_setlink+0x225/0x320 net/core/rtnetlink.c:2303
 rtnetlink_rcv_msg+0x3eb/0xb70 net/core/rtnetlink.c:4285
 netlink_rcv_skb+0x14f/0x3c0 net/netlink/af_netlink.c:2432
 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:4297
 netlink_unicast_kernel net/netlink/af_netlink.c:1286 [inline]
 netlink_unicast+0x45d/0x640 net/netlink/af_netlink.c:1312
 netlink_sendmsg+0x7c4/0xc60 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xce/0x110 net/socket.c:656
 ___sys_sendmsg+0x70a/0x840 net/socket.c:2062
 __sys_sendmsg+0xb9/0x140 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2103
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
RIP: 0033:0x440269
RSP: 002b:00007ffe4b87e128 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440269
RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000401af0
R13: 0000000000401b80 R14: 0000000000000000 R15: 0000000000000000
Code: 80 3c 02 00 75 5c 49 8b 84 24 c0 0a 00 00 48 8d 14 5b 48 8d 1c d0 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 12 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 04 84 c0 75 16 44 88 6b 
RIP: dummy_set_vf_trust+0x68/0xb0 drivers/net/dummy.c:243 RSP: ffff888096ef72b0
CR2: fffffbfffd600002
---[ end trace 4dd7c86d2275198f ]---

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/08/02 23:27 linux-4.14.y 10d6aa565d05 3faab807 .config console log report syz C ci2-linux-4-14
2019/09/05 11:19 linux-4.14.y 01fd1694b93c 040fda58 .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.