------- Comment From cha...@us.ibm.com 2018-05-29 14:59 EDT------- Are we still seeing this issue reproduced or could this be related to some other bug that has also been seen?
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1770784 Title: ISST-LTE:KVM:Ubuntu1804:BostonLC:boslcp4g4:ubuntu1604:P8 compat: guest crashes in apparmor_file_alloc_security() Status in The Ubuntu-power-systems project: Triaged Status in linux package in Ubuntu: New Bug description: Test was running an Ubuntu 16.04 guest with a Ubuntu 18.04 host when the guest dumped a vmcore. According to the dump, the crash is actually a BUG_ON() raised from apparmor_file_alloc_security() having called aa_begin_current_label() which calls aa_current_raw_label() that in turn calls aa_cred_raw_label() where the BUG_ON() resides: static inline struct aa_label *aa_cred_raw_label(const struct cred *cred) { struct aa_task_ctx *ctx = cred_ctx(cred); BUG_ON(!ctx || !ctx->label); return ctx->label; } Now, the warnings we previously had seen raised from aa_file_perm() may have been related since rcu_dereference() as fctx->label is NULL. fctx = file_ctx(file); rcu_read_lock(); flabel = rcu_dereference(fctx->label); AA_BUG(!flabel); KERNEL: /usr/lib/debug/boot/vmlinux-4.4.0-124-generic DUMPFILE: dump.201805110830 [PARTIAL DUMP] CPUS: 32 DATE: Fri May 11 06:30:35 2018 UPTIME: 03:40:43 LOAD AVERAGE: 102.77, 103.38, 100.54 TASKS: 862 NODENAME: boslcp4g4 RELEASE: 4.4.0-124-generic VERSION: #148-Ubuntu SMP Wed May 2 13:02:22 UTC 2018 MACHINE: ppc64le (2134 Mhz) MEMORY: 16 GB PANIC: "kernel BUG at /build/linux-VRGJAN/linux-4.4.0/security/apparmor/include/context.h:69!" PID: 18397 COMMAND: "chgrp" TASK: c00000035be322c0 [THREAD_INFO: c00000035b5c0000] CPU: 10 STATE: TASK_RUNNING (PANIC) crash> bt PID: 18397 TASK: c00000035be322c0 CPU: 10 COMMAND: "chgrp" #0 [c00000035b5c3430] crash_kexec at c000000000176274 #1 [c00000035b5c35d0] die at c000000000020ef8 #2 [c00000035b5c3660] _exception at c000000000021244 #3 [c00000035b5c37f0] program_check_common at c000000000006208 Program Check [700] exception frame: R0: c0000000004923e4 R1: c00000035b5c3ae0 R2: c0000000015fa700 R3: c0000000fcd01a00 R4: 0000000000000001 R5: ffffffffffffffc0 R6: c0000000fcd01b00 R7: 00000003fe8d0000 R8: c00000000163a700 R9: 0000000000000001 R10: 0000000000000000 R11: 0000000000000000 R12: c0000000004fd880 R13: c000000007b06400 R14: 0000000000000000 R15: 0000000000000000 R16: 0000000000000013 R17: 0000000000000000 R18: 00003fffb7501468 R19: 0000000000000000 R20: 00003fffb74ff7e0 R21: 0000000000000000 R22: 0000000000000000 R23: 00003fffdf3cbd40 R24: ffffffff90000001 R25: 0000000000000041 R26: fffffffffffff000 R27: c00000035b5c3dd0 R28: c0000000016342f8 R29: c0000000fcd01a00 R30: c0000000fcd01a00 R31: 0000000000000000 NIP: c0000000004fd8c8 MSR: 8000000000029033 OR3: c0000000004923e0 CTR: c0000000004fd880 LR: c0000000004923e4 XER: 0000000000000000 CCR: 0000000024004248 MQ: 0000000000000001 DAR: c000000328004288 DSISR: c00000035b5c39e0 Syscall Result: 0000000000000000 #4 [c00000035b5c3ae0] apparmor_file_alloc_security at c0000000004fd8c8 [Link Register] [c00000035b5c3ae0] security_file_alloc at c0000000004923e4 #5 [c00000035b5c3b50] security_file_alloc at c0000000004923e4 (unreliable) #6 [c00000035b5c3b90] get_empty_filp at c0000000002e7010 #7 [c00000035b5c3c10] path_openat at c0000000002faa2c #8 [c00000035b5c3c90] do_filp_open at c0000000002fc9bc #9 [c00000035b5c3db0] do_sys_open at c0000000002e3150 #10 [c00000035b5c3e30] system_call at c000000000009484 System Call [c01] exception frame: R0: 0000000000000005 R1: 00003fffdf3cb8c0 R2: 00003fffb7507e00 R3: 00000100270514b0 R4: 0000000000080000 R5: 00003fffb7501ef8 R6: 0000000000000008 R7: ffffffff90000001 R8: 00003fffdf3cbd40 R9: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 00003fffb750a190 NIP: 00003fffb74dbdac MSR: 800000000280f033 OR3: 00000100270514b0 CTR: 0000000000000000 LR: 00003fffb74b7034 XER: 0000000000000000 CCR: 0000000044004442 MQ: 0000000000000001 DAR: 00003fffb7480000 DSISR: 0000000040000000 Syscall Result: fffffffffffffffe To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-power-systems/+bug/1770784/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
