FYI, we noticed the following commit (built with gcc-7):

commit: 780a16e323917b78004645d94400296a5e0826f3 ("Patch to do key type autoloading v2")
https://kernel.googlesource.com/pub/scm/linux/kernel/git/mbroz/linux.git dm-cryptsetup

in testcase: trinity
with following parameters:

	runtime: 300s

test-description: Trinity is a linux system call fuzz tester.
test-url: http://codemonkey.org.uk/projects/trinity/


on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 4G

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+----------------------------------------------------+----------+------------+
|                                                    | v5.3-rc4 | 780a16e323 |
+----------------------------------------------------+----------+------------+
| boot_successes                                     | 3374     | 13         |
| boot_failures                                      | 50       | 18         |
| invoked_oom-killer:gfp_mask=0x                     | 26       | 1          |
| Mem-Info                                           | 26       | 1          |
| RIP:copy_user_generic_string                       | 5        |            |
| kernel_BUG_at_security/keys/keyring.c              | 12       |            |
| invalid_opcode:#[##]                               | 12       |            |
| RIP:__key_link_begin                               | 12       |            |
| Kernel_panic-not_syncing:Fatal_exception           | 12       | 1          |
| BUG:soft_lockup-CPU##stuck_for#s                   | 2        |            |
| RIP:clear_page_rep                                 | 1        |            |
| Kernel_panic-not_syncing:softlockup:hung_tasks     | 2        |            |
| BUG:kernel_hang_in_boot_stage                      | 8        |            |
| RIP:__memcpy                                       | 1        |            |
| BUG:kernel_hang_in_boot-around-mounting-root_stage | 1        |            |
| BUG:kernel_reboot-without-warning_in_test_stage    | 1        |            |
| WARNING:at_lib/vsprintf.c:#format_decode           | 0        | 16         |
| RIP:format_decode                                  | 0        | 16         |
| general_protection_fault:#[##]                     | 0        | 1          |
| RIP:string_nocheck                                 | 0        | 1          |
+----------------------------------------------------+----------+------------+


If you fix the issue, kindly add following tag
Reported-by: kernel test robot <rong.a.chen@intel.com>


[   96.204959] WARNING: CPU: 1 PID: 2265 at lib/vsprintf.c:2359 format_decode+0x3dd/0x3f0
[   96.214488] Modules linked in: ieee802154_socket ieee802154 bridge stp llc sr_mod cdrom intel_rapl_msr sg ppdev af_key hidp cmtp kernelcapi bnep rfcomm bluetooth ecdh_generic ecc rfkill can_bcm can_raw can pptp gre l2tp_ppp l2tp_netlink l2tp_core ip6_udp_tunnel udp_tunnel pppoe pppox ppp_generic slhc intel_rapl_common crct10dif_pclmul crypto_user crc32_pclmul nfnetlink ghash_clmulni_intel scsi_transport_iscsi dccp_ipv6 atm aesni_intel sctp libcrc32c crypto_simd crc32c_intel dccp_ipv4 cryptd dccp glue_helper joydev pcspkr serio_raw bochs_drm parport_pc drm_vram_helper ttm parport drm_kms_helper floppy syscopyarea sysfillrect sysimgblt fb_sys_fops ata_generic pata_acpi drm i2c_piix4 ata_piix libata ip_tables
[   96.279994] CPU: 1 PID: 2265 Comm: trinity-c2 Not tainted 5.3.0-rc4-00001-g780a16e323917 #1
[   96.294201] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[   96.305126] RIP: 0010:format_decode+0x3dd/0x3f0
[   96.312620] Code: ff ff 48 8d 42 02 b9 4c 00 00 00 48 89 04 24 e9 db fc ff ff 0f be f2 48 c7 c7 80 15 fc b3 c6 05 1b b5 d9 00 01 e8 63 e8 63 ff <0f> 0b 48 8b 04 24 e9 04 ff ff ff 0f 1f 84 00 00 00 00 00 89 f0 c1
[   96.331681] RSP: 0018:ffffbe4b0058fd48 EFLAGS: 00010282
[   96.337426] RAX: 0000000000000000 RBX: ffffbe4b0058fd78 RCX: 0000000000000000
[   96.343707] RDX: ffff9a49ffd27200 RSI: ffff9a49ffd17778 RDI: ffff9a49ffd17778
[   96.349607] RBP: ffff9a493aaa142c R08: 0000000000000322 R09: 0000000000aaaaaa
[   96.355159] R10: ffffbe4b0058fec0 R11: ffff9a4950ae2070 R12: ffffbe4b0058fe48
[   96.361237] R13: 0000000000000038 R14: ffffbe4b0058fdf8 R15: ffff9a493aaa142c
[   96.367489] FS:  00007fc509049740(0000) GS:ffff9a49ffd00000(0000) knlGS:0000000000000000
[   96.373905] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   96.378953] CR2: 0000000000000000 CR3: 000000007a442000 CR4: 00000000000406e0
[   96.384394] Call Trace:
[   96.388238]  vsnprintf+0x65/0x4d0
[   96.392840]  __request_module+0xb7/0x450
[   96.396968]  ? kasprintf+0x49/0x70
[   96.400972]  key_type_lookup+0xba/0x110
[   96.406382]  __x64_sys_request_key+0xcf/0x190
[   96.411046]  do_syscall_64+0x5b/0x1f0
[   96.415363]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   96.419802] RIP: 0033:0x7fc5089561c9
[   96.424822] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 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 73 01 c3 48 8b 0d 97 dc 2c 00 f7 d8 64 89 01 48
[   96.439124] RSP: 002b:00007fffc6696be8 EFLAGS: 00000246 ORIG_RAX: 00000000000000f9
[   96.453973] RAX: ffffffffffffffda RBX: 00000000000000f9 RCX: 00007fc5089561c9
[   96.464762] RDX: 00007fc506b5700c RSI: 00007fc506b57004 RDI: 00007fc506b57000
[   96.477464] RBP: 00007fc509034000 R08: 0000000004000000 R09: 0000000000000000
[   96.491136] R10: fffffffffffffffd R11: 0000000000000246 R12: 00007fc509034058
[   96.504153] R13: 00007fc5090496b0 R14: 0000000000000000 R15: 00007fc509034000
[   96.509849] ---[ end trace 79467a168956abee ]---


To reproduce:

        # build kernel
	cd linux
	cp config-5.3.0-rc4-00001-g780a16e323917 .config
	make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 olddefconfig prepare modules_prepare bzImage

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email



Thanks,
Rong Chen