Oops (request_key_auth_describe) while running cve-2016-7042 from LTP

[Sachin Sant]

While running LTP tests (specifically cve-2016-7042) against 5.3-rc6
(commit 4a64489cf8) on a POWER9 LPAR, following problem is seen

[ 3373.814425] FS-Cache: Netfs 'nfs' registered for caching
[ 7695.250230] Clock: inserting leap second 23:59:60 UTC
[ 8074.351033] BUG: Kernel NULL pointer dereference at 0x00000038
[ 8074.351046] Faulting instruction address: 0xc0000000004ddf30
[ 8074.351052] Oops: Kernel access of bad area, sig: 11 [#1]
[ 8074.351056] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
[ 8074.351067] Dumping ftrace buffer:
[ 8074.351081]    (ftrace buffer empty)
[ 8074.351085] Modules linked in: nfsv3 nfs_acl nfs lockd grace fscache sctp tun brd vfat fat fuse xfs overlay loop iscsi_target_mod target_core_mod macsec tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag binfmt_misc bridge stp llc ip6t_rpfilter ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute ip6table_nat ip6table_mangle ip6table_raw iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c iptable_mangle iptable_raw ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter sunrpc uio_pdrv_genirq pseries_rng sg uio ip_tables ext4 mbcache jbd2 sr_mod cdrom sd_mod ibmvscsi ibmveth scsi_transport_srp dm_mirror dm_region_hash dm_log dm_mod [last unloaded: dummy_del_mod]
[ 8074.351153] CPU: 10 PID: 8314 Comm: cve-2016-7042 Tainted: G           O      5.3.0-rc6-autotest #1
[ 8074.351158] NIP:  c0000000004ddf30 LR: c0000000004ddef4 CTR: c0000000004ddea0
[ 8074.351164] REGS: c0000000e74fb800 TRAP: 0300   Tainted: G           O       (5.3.0-rc6-autotest)
[ 8074.351170] MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 88002482  XER: 00000000
[ 8074.351177] CFAR: c00000000000dfc4 DAR: 0000000000000038 DSISR: 40000000 IRQMASK: 0 
[ 8074.351177] GPR00: c0000000004ddef4 c0000000e74fba90 c0000000013cc200 c0000008b0d7039b 
[ 8074.351177] GPR04: c0000008b0dabe3e 0000000000000007 00090a0200000904 c0000008b0d80000 
[ 8074.351177] GPR08: 00000000000003a2 0000000000000001 000000000000039b c000000000d03ac0 
[ 8074.351177] GPR12: c0000000004ddea0 c00000001ec5dc00 0000000000000000 0000000000000000 
[ 8074.351177] GPR16: 0000000000000000 0000000000000002 000000001b010000 0000000000000000 
[ 8074.351177] GPR20: 000000003bc24df7 c0000000e74fbc28 0000000000000049 0000000000000052 
[ 8074.351177] GPR24: 000000000000002d c0000000ffe30780 c0000008a991d800 000000000000002d 
[ 8074.351177] GPR28: 0000000000000069 0000000000000000 c0000000ffe30780 c0000008a991d800 
[ 8074.351224] NIP [c0000000004ddf30] request_key_auth_describe+0x90/0xd0
[ 8074.351230] LR [c0000000004ddef4] request_key_auth_describe+0x54/0xd0
[ 8074.351233] Call Trace:
[ 8074.351237] [c0000000e74fba90] [c0000000004ddef4] request_key_auth_describe+0x54/0xd0 (unreliable)
[ 8074.351244] [c0000000e74fbb10] [c0000000004df718] proc_keys_show+0x308/0x4c0
[ 8074.351250] [c0000000e74fbcc0] [c000000000404950] seq_read+0x3d0/0x540
[ 8074.351255] [c0000000e74fbd40] [c0000000004865e0] proc_reg_read+0x90/0x110
[ 8074.351261] [c0000000e74fbd70] [c0000000003c901c] __vfs_read+0x3c/0x70
[ 8074.351267] [c0000000e74fbd90] [c0000000003c9104] vfs_read+0xb4/0x1b0
[ 8074.351272] [c0000000e74fbdd0] [c0000000003c95ec] ksys_read+0x7c/0x130
[ 8074.351277] [c0000000e74fbe20] [c00000000000b388] system_call+0x5c/0x70
[ 8074.351281] Instruction dump:
[ 8074.351285] 2b890001 419e002c 38210080 e8010010 eba1ffe8 ebc1fff0 ebe1fff8 7c0803a6 
[ 8074.351292] 4e800020 60000000 60000000 60420000 <e8bd003a> e8dd0030 3c82ff93 7fc3f378 
[ 8074.351301] ---[ end trace d3304a3a5a0a0ca1 ]â

These CVE tests from LTP were recently added to the automated regression test bucket that
I run against upstream. I canât tell if this is a regression or a new problem.

Thanks
-Sachin