Ubuntu
qemu package

QEMU S/390x sqxbr (128-bit IEEE 754 square root) crashes qemu-system-s390x

  1. Focal (20.04)
  2. Bug #1883984
Bug #1883984 reported by Nelson H F Beebe
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
QEMU
Fix Released
Undecided
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qemu (Ubuntu)
Fix Released
Undecided
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Focal
Fix Released
Medium
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Bug Description

[Impact]

 * An instruction was described wrong so that on usage the program would
   crash.

[Test Case]

 * Run s390x in emulation and there use this program:
   For simplicity and speed you can use KVM guest as usual on s390x, that
   after prep&install&compile of the test you run in qemu-tcg like:

   $ sudo qemu-system-s390x -machine s390-ccw-virtio,accel=tcg -cpu max,zpci=on -serial mon:stdio -display none -m 4096 -nic user,model=virtio,hostfwd=tcp::2222-:22 -drive file=/var/lib/uvtool/libvirt/images/focal-sqxbr.qcow,if=none,id=drive-virtio-disk0,format=qcow2,cache=none -device virtio-blk-ccw,devno=fe.0.0001,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1,scsi=off
   Obviously is you have no s390x access you need to use emulation right
   away.

 * Build and run failing program
   $ sudo apt install clang
   $ cat > bug-sqrtl-one-line.c << EOF
int main(void) { volatile long double x, r; x = 4.0L; __asm__
__volatile__("sqxbr %0, %1" : "=f" (r) : "f" (x)); return (0);}
EOF
   $ cc bug-sqrtl-one-line.c
   $ ./a.out
   Segmentation fault (core dumped)

   qemu is dead by now as long as the bug is present

[Regression Potential]

 * The change only modifies 128 bit square root on s390x so regressions
   should be limited to exactly that - which formerly before this fix was
   a broken instruction.

[Other Info]

 * n/a

---

In porting software to guest Ubuntu 18.04 and 20.04 VMs for S/390x, I discovered
that some of my own numerical programs, and also a GNU configure script for at
least one package with CC=clang, would cause an instant crash of the VM, sometimes
also destroying recently opened files, and producing long strings of NUL characters
in /var/log/syslog in the S/390 guest O/S.

Further detective work narrowed the cause of the crash down to a single IBM S/390
instruction: sqxbr (128-bit IEEE 754 square root). Here is a one-line program
that when compiled and run on a VM hosted on QEMUcc emulator version 4.2.0
(Debian 1:4.2-3ubuntu6.1) [hosted on Ubuntu 20.04 on a Dell Precision 7920
workstation with an Intel Xeon Platinum 8253 CPU], and also on QEMU emulator
version 5.0.0, reproducibly produces a VM crash under qemu-system-s390x.

% cat bug-sqrtl-one-line.c
int main(void) { volatile long double x, r; x = 4.0L; __asm__ __volatile__("sqxbr %0, %1" : "=f" (r) : "f" (x)); return (0);}

% cc bug-sqrtl-one-line.c && ./a.out
Segmentation fault (core dumped)

The problem code may be the function float128_sqrt() defined in qemu-5.0.0/fpu/softfloat.c
starting at line 7619. I have NOT attempted to run the qemu-system-s390x executable
under a debugger. However, I observe that S/390 is the only CPU family that I know of,
except possibly for a Fujitsu SPARC-64, that has a 128-bit square root in hardware.
Thus, this instruction bug may not have been seen before.

See original description

Related branches

~paelzer/ubuntu/+source/qemu:focal-SRU-august2020-1890154-1883984-1891203-1891877
Rafael David Tinoco (community): Approve
Canonical Server: Pending requested
git-ubuntu developers: Pending requested
Diff: 10691 lines (+9839/-7)
133 files modified
debian/changelog (+86/-0)
debian/patches/series (+131/-1)
debian/patches/stable/lp-1891877-9p-Lock-directory-streams-with-a-CoMutex.patch (+74/-0)
debian/patches/stable/lp-1891877-9p-local-always-return-1-on-error-in-local_unlinkat_.patch (+91/-0)
debian/patches/stable/lp-1891877-9p-proxy-Fix-export_flags.patch (+49/-0)
debian/patches/stable/lp-1891877-9pfs-include-linux-limits.h-for-XATTR_SIZE_MAX.patch (+43/-0)
debian/patches/stable/lp-1891877-9pfs-local-Fix-possible-memory-leak-in-local_link.patch (+44/-0)
debian/patches/stable/lp-1891877-9pfs-local-ignore-O_NOATIME-if-we-don-t-have-permiss.patch (+67/-0)
debian/patches/stable/lp-1891877-Fix-double-free-issue-in-qemu_set_log_filename.patch (+41/-0)
debian/patches/stable/lp-1891877-Fix-tulip-breakage.patch (+65/-0)
debian/patches/stable/lp-1891877-Revert-qemu-options.hx-Update-for-reboot-timeout-par.patch (+43/-0)
debian/patches/stable/lp-1891877-Revert-vnc-allow-fall-back-to-RAW-encoding.patch (+77/-0)
debian/patches/stable/lp-1891877-Update-version-for-4.2.1-release.patch (+24/-0)
debian/patches/stable/lp-1891877-blkdebug-Allow-taking-unsharing-permissions.patch (+209/-0)
debian/patches/stable/lp-1891877-block-Add-bdrv_qapi_perm_to_blk_perm.patch (+87/-0)
debian/patches/stable/lp-1891877-block-Avoid-memleak-on-qcow2-image-info-failure.patch (+41/-0)
debian/patches/stable/lp-1891877-block-Call-attention-to-truncation-of-long-NBD-expor.patch (+100/-0)
debian/patches/stable/lp-1891877-block-Fix-VM-size-field-width-in-snapshot-dump.patch (+58/-0)
debian/patches/stable/lp-1891877-block-backup-fix-memory-leak-in-bdrv_backup_top_appe.patch (+55/-0)
debian/patches/stable/lp-1891877-block-bdrv_set_backing_bs-fix-use-after-free.patch (+122/-0)
debian/patches/stable/lp-1891877-block-fix-memleaks-in-bdrv_refresh_filename.patch (+68/-0)
debian/patches/stable/lp-1891877-compat-disable-edid-on-correct-virtio-gpu-device.patch (+49/-0)
debian/patches/stable/lp-1891877-display-bochs-display-fix-memory-leak.patch (+42/-0)
debian/patches/stable/lp-1891877-dp8393x-Always-update-RRA-pointers-and-sequence-numb.patch (+52/-0)
debian/patches/stable/lp-1891877-dp8393x-Always-use-32-bit-accesses.patch (+167/-0)
debian/patches/stable/lp-1891877-dp8393x-Clean-up-endianness-hacks.patch (+71/-0)
debian/patches/stable/lp-1891877-dp8393x-Clear-RRRA-command-register-bit-only-when-ap.patch (+56/-0)
debian/patches/stable/lp-1891877-dp8393x-Clear-descriptor-in_use-field-to-release-pac.patch (+55/-0)
debian/patches/stable/lp-1891877-dp8393x-Don-t-clobber-packet-checksum.patch (+45/-0)
debian/patches/stable/lp-1891877-dp8393x-Don-t-reset-Silicon-Revision-register.patch (+51/-0)
debian/patches/stable/lp-1891877-dp8393x-Don-t-stop-reception-upon-RBE-interrupt-asse.patch (+137/-0)
debian/patches/stable/lp-1891877-dp8393x-Have-dp8393x_receive-return-the-packet-size.patch (+68/-0)
debian/patches/stable/lp-1891877-dp8393x-Implement-packet-size-limit-and-RBAE-interru.patch (+57/-0)
debian/patches/stable/lp-1891877-dp8393x-Mask-EOL-bit-from-descriptor-addresses.patch (+98/-0)
debian/patches/stable/lp-1891877-dp8393x-Pad-frames-to-word-or-long-word-boundary.patch (+113/-0)
debian/patches/stable/lp-1891877-dp8393x-Update-LLFA-and-CRDA-registers-from-rx-descr.patch (+75/-0)
debian/patches/stable/lp-1891877-dp8393x-Use-long-word-aligned-RRA-pointers-in-32-bit.patch (+60/-0)
debian/patches/stable/lp-1891877-dump-Fix-writing-of-ELF-section.patch (+51/-0)
debian/patches/stable/lp-1891877-hmp-vnc-Fix-info-vnc-list-leak.patch (+54/-0)
debian/patches/stable/lp-1891877-hostmem-don-t-use-mbind-if-host-nodes-is-empty.patch (+61/-0)
debian/patches/stable/lp-1891877-hw-arm-cubieboard-use-ARM-Cortex-A8-as-the-default-C.patch (+59/-0)
debian/patches/stable/lp-1891877-hw-arm-smmuv3-Align-stream-table-base-address-to-tab.patch (+83/-0)
debian/patches/stable/lp-1891877-hw-arm-smmuv3-Apply-address-mask-to-linear-strtab-ba.patch (+59/-0)
debian/patches/stable/lp-1891877-hw-arm-smmuv3-Check-stream-IDs-against-actual-table-.patch (+63/-0)
debian/patches/stable/lp-1891877-hw-arm-smmuv3-Correct-SMMU_BASE_ADDR_MASK-value.patch (+52/-0)
debian/patches/stable/lp-1891877-hw-arm-smmuv3-Report-F_STE_FETCH-fault-address-in-co.patch (+55/-0)
debian/patches/stable/lp-1891877-hw-arm-smmuv3-Use-correct-bit-positions-in-EVT_SET_A.patch (+58/-0)
debian/patches/stable/lp-1891877-hw-i386-amd_iommu.c-Fix-corruption-of-log-events-pas.patch (+49/-0)
debian/patches/stable/lp-1891877-hw-intc-arm_gicv3_kvm-Stop-wrongly-programming-GICR_.patch (+66/-0)
debian/patches/stable/lp-1891877-i386-Resolve-CPU-models-to-v1-by-default.patch (+91/-0)
debian/patches/stable/lp-1891877-ide-Fix-incorrect-handling-of-some-PRDTs-in-ide_dma_.patch (+99/-0)
debian/patches/stable/lp-1891877-iotests-026-Move-v3-exclusive-test-to-new-file.patch (+232/-0)
debian/patches/stable/lp-1891877-iotests-026-Test-EIO-on-allocation-in-a-data-file.patch (+107/-0)
debian/patches/stable/lp-1891877-iotests-026-Test-EIO-on-preallocated-zero-cluster.patch (+97/-0)
debian/patches/stable/lp-1891877-iotests-283-Use-consistent-size-for-source-and-targe.patch (+57/-0)
debian/patches/stable/lp-1891877-iotests-Fix-IMGOPTSSYNTAX-for-nbd.patch (+42/-0)
debian/patches/stable/lp-1891877-iotests-Fix-nonportable-use-of-od-endian.patch (+69/-0)
debian/patches/stable/lp-1891877-iotests-Test-copy-offloading-with-external-data-file.patch (+71/-0)
debian/patches/stable/lp-1891877-iotests-add-test-for-backup-top-failure-on-permissio.patch (+19/-6)
debian/patches/stable/lp-1891877-m68k-Fix-regression-causing-Single-Step-via-GDB-RSP-.patch (+108/-0)
debian/patches/stable/lp-1891877-migration-Rate-limit-inside-host-pages.patch (+157/-0)
debian/patches/stable/lp-1891877-migration-colo-fix-use-after-free-of-local_err.patch (+39/-0)
debian/patches/stable/lp-1891877-migration-ram-fix-use-after-free-of-local_err.patch (+39/-0)
debian/patches/stable/lp-1891877-migration-test-ppc64-fix-FORTH-test-program.patch (+67/-0)
debian/patches/stable/lp-1891877-net-Do-not-include-a-newline-in-the-id-of-nic-device.patch (+43/-0)
debian/patches/stable/lp-1891877-numa-properly-check-if-numa-is-supported.patch (+75/-0)
debian/patches/stable/lp-1891877-numa-remove-not-needed-check.patch (+52/-0)
debian/patches/stable/lp-1891877-ppc-ppc405_boards-Remove-unnecessary-NULL-check.patch (+63/-0)
debian/patches/stable/lp-1891877-qapi-better-document-NVMe-blockdev-device-parameter.patch (+49/-0)
debian/patches/stable/lp-1891877-qcow2-List-autoclear-bit-names-in-header.patch (+208/-0)
debian/patches/stable/lp-1891877-qcow2-update_refcount-Reset-old_table_index-after-qc.patch (+43/-0)
debian/patches/stable/lp-1891877-qemu-ga-document-vsock-listen-in-the-man-page.patch (+70/-0)
debian/patches/stable/lp-1891877-qemu-nbd-Close-inherited-stderr.patch (+46/-0)
debian/patches/stable/lp-1891877-qga-Fix-undefined-C-behavior.patch (+53/-0)
debian/patches/stable/lp-1891877-qga-Installer-Wait-for-installation-to-finish.patch (+42/-0)
debian/patches/stable/lp-1891877-qga-win-Handle-VSS_E_PROVIDER_ALREADY_REGISTERED-err.patch (+47/-0)
debian/patches/stable/lp-1891877-qga-win-prevent-crash-when-executing-guest-file-read.patch (+55/-0)
debian/patches/stable/lp-1891877-runstate-ignore-finishmigrate-prelaunch-transition.patch (+69/-0)
debian/patches/stable/lp-1891877-s390x-adapter-routes-error-handling.patch (+84/-0)
debian/patches/stable/lp-1891877-scsi-qemu-pr-helper-Fix-out-of-bounds-access-to-trnp.patch (+102/-0)
debian/patches/stable/lp-1891877-sheepdog-Consistently-set-bdrv_has_zero_init_truncat.patch (+54/-0)
debian/patches/stable/lp-1891877-spapr-Fix-failure-path-for-attempting-to-hot-unplug-.patch (+42/-0)
debian/patches/stable/lp-1891877-target-arm-Clear-tail-in-gvec_fmul_idx_-gvec_fmla_id.patch (+47/-0)
debian/patches/stable/lp-1891877-target-arm-Correct-definition-of-PMCRDP.patch (+47/-0)
debian/patches/stable/lp-1891877-target-arm-fix-TCG-leak-for-fcvt-half-double.patch (+54/-0)
debian/patches/stable/lp-1891877-target-arm-monitor-query-cpu-model-expansion-crashed.patch (+66/-0)
debian/patches/stable/lp-1891877-target-ppc-Fix-mtmsr-d-L-1-variant-that-loses-interr.patch (+163/-0)
debian/patches/stable/lp-1891877-target-ppc-Fix-rlwinm-on-ppc64.patch (+67/-0)
debian/patches/stable/lp-1891877-target-xtensa-fix-pasto-in-pfwait.r-opcode-name.patch (+36/-0)
debian/patches/stable/lp-1891877-tcg-i386-Fix-INDEX_op_dup2_vec.patch (+45/-0)
debian/patches/stable/lp-1891877-tcg-mips-mips-sync-encode-error.patch (+57/-0)
debian/patches/stable/lp-1891877-tests-fix-modules-test-duplicate-test-case-error.patch (+54/-0)
debian/patches/stable/lp-1891877-tests-ide-test-Create-a-single-unit-test-covering-mo.patch (+228/-0)
debian/patches/stable/lp-1891877-vhost-user-blk-delete-virtioqueues-in-unrealize-to-f.patch (+75/-0)
debian/patches/stable/lp-1891877-vhost-user-gpu-Release-memory-returned-by-vu_queue_p.patch (+67/-0)
debian/patches/stable/lp-1891877-virtio-9p-device-fix-memleak-in-virtio_9p_device_unr.patch (+49/-0)
debian/patches/stable/lp-1891877-virtio-add-ability-to-delete-vq-through-a-pointer.patch (+71/-0)
debian/patches/stable/lp-1891877-virtio-balloon-fix-free-page-hinting-check-on-unreal.patch (+51/-0)
debian/patches/stable/lp-1891877-virtio-balloon-fix-free-page-hinting-without-an-ioth.patch (+116/-0)
debian/patches/stable/lp-1891877-virtio-balloon-unref-the-iothread-when-unrealizing.patch (+49/-0)
debian/patches/stable/lp-1891877-virtio-crypto-do-delete-ctrl_vq-in-virtio_crypto_dev.patch (+61/-0)
debian/patches/stable/lp-1891877-virtio-make-virtio_delete_queue-idempotent.patch (+37/-0)
debian/patches/stable/lp-1891877-virtio-pmem-do-delete-rq_vq-in-virtio_pmem_unrealize.patch (+45/-0)
debian/patches/stable/lp-1891877-virtio-reset-region-cache-when-on-queue-deletion.patch (+40/-0)
debian/patches/stable/lp-1891877-vpc-Don-t-round-up-already-aligned-BAT-sizes.patch (+55/-0)
debian/patches/stable/lp-1891877-xen-9pfs-yield-when-there-isn-t-enough-room-on-the-r.patch (+96/-0)
debian/patches/stable/lp-1891877-xen-block-Fix-double-qlist-remove-and-request-leak.patch (+163/-0)
debian/patches/ubuntu/CVE-2020-10761.patch (+149/-0)
debian/patches/ubuntu/CVE-2020-12829-2.patch (+55/-0)
debian/patches/ubuntu/CVE-2020-12829-3.patch (+41/-0)
debian/patches/ubuntu/CVE-2020-12829-4.patch (+42/-0)
debian/patches/ubuntu/CVE-2020-12829-5.patch (+28/-0)
debian/patches/ubuntu/CVE-2020-12829-6.patch (+129/-0)
debian/patches/ubuntu/CVE-2020-12829-7.patch (+61/-0)
debian/patches/ubuntu/CVE-2020-12829-pre1.patch (+159/-0)
debian/patches/ubuntu/CVE-2020-12829-pre2.patch (+134/-0)
debian/patches/ubuntu/CVE-2020-12829-pre3.patch (+42/-0)
debian/patches/ubuntu/CVE-2020-12829-pre4.patch (+95/-0)
debian/patches/ubuntu/CVE-2020-12829.patch (+261/-0)
debian/patches/ubuntu/CVE-2020-13253.patch (+122/-0)
debian/patches/ubuntu/CVE-2020-13361.patch (+60/-0)
debian/patches/ubuntu/CVE-2020-13362-1.patch (+51/-0)
debian/patches/ubuntu/CVE-2020-13362-2.patch (+36/-0)
debian/patches/ubuntu/CVE-2020-13362-3.patch (+97/-0)
debian/patches/ubuntu/CVE-2020-13659.patch (+47/-0)
debian/patches/ubuntu/CVE-2020-13754-1.patch (+81/-0)
debian/patches/ubuntu/CVE-2020-13754-2.patch (+59/-0)
debian/patches/ubuntu/CVE-2020-13800.patch (+59/-0)
debian/patches/ubuntu/CVE-2020-14415.patch (+33/-0)
debian/patches/ubuntu/CVE-2020-15863.patch (+58/-0)
debian/patches/ubuntu/CVE-2020-16092.patch (+40/-0)
debian/patches/ubuntu/lp-1883984-target-s390x-Fix-SQXBR.patch (+37/-0)
debian/patches/ubuntu/lp-1890154-s390x-protvirt-allow-to-IPL-secure-guests-with-no-re.patch (+52/-0)
~paelzer/ubuntu/+source/qemu:groovy-merge-pick-5.0-14
Rafael David Tinoco (community): Approve
Canonical Server: Pending requested
Canonical Server packageset reviewers: Pending requested
Diff: 150 lines (+105/-0)
5 files modified
debian/changelog (+10/-0)
debian/patches/lp-1890154-s390x-protvirt-allow-to-IPL-secure-guests-with-no-re.patch (+52/-0)
debian/patches/series (+2/-0)
debian/patches/ubuntu/lp-1883984-target-s390x-Fix-SQXBR.patch (+37/-0)
debian/rules (+4/-0)

CVE References

Revision history for this message
Bruno Haible (bruno-clisp) wrote :

Another way to reproduce this bug is with qemu-s390x and a cross-compiled binary:

$ s390x-linux-gnu-gcc-5 -static -o bug-sqrtl-one-line.s390x bug-sqrtl-one-line.c
$ qemu-s390x bug-sqrtl-one-line.s390x
Segmentation fault (core dumped)

Find attached the binary.

Revision history for this message
Richard Henderson (rth) wrote :

With --enable-debug,

qemu-s390x: /home/rth/qemu/qemu/include/tcg/tcg.h:687: temp_idx: Assertion `n >= 0 && n < tcg_ctx->nb_temps' failed.

which turns out to be related to a null-pointer temporary.

Changed in qemu:
status: New → Confirmed
Revision history for this message
Bruno Haible (bruno-clisp) wrote :

I confirm that the patch https://lists.gnu.org/archive/html/qemu-s390x/2020-06/msg00213.html fixes the issue, both for qemu-s390x and qemu-system-s390x.

Thanks Richard!

Richard Henderson (rth)
Changed in qemu:
status: Confirmed → Fix Committed
Christian Ehrhardt  (paelzer)
Changed in qemu (Ubuntu):
status: New → In Progress
assignee: nobody → Christian Ehrhardt  (paelzer)
Christian Ehrhardt  (paelzer)
Changed in qemu (Ubuntu Focal):
status: New → Triaged
importance: Undecided → Medium
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package qemu - 1:5.0-5ubuntu4

---------------
qemu (1:5.0-5ubuntu4) groovy; urgency=medium

  * xen: provide compat links to what libxen-dev reports where to find
    the binaries (LP: #1890005)
  * d/p/ubuntu/lp-1883984-target-s390x-Fix-SQXBR.patch: avoid crash on
    SQXBR (LP: #1883984)
  * d/p/lp-1890154-*: fix -no-reboot on s390x secure boot (LP: #1890154)

 -- Christian Ehrhardt <email address hidden> Mon, 03 Aug 2020 07:15:28 +0200

Changed in qemu (Ubuntu):
status: In Progress → Fix Released
Christian Ehrhardt  (paelzer)
description: updated
Revision history for this message
Christian Ehrhardt  (paelzer) wrote :

Note: final upstream commit link https://git.qemu.org/?p=qemu.git;a=commit;h=9bf728a09bf7509b27543664f9cca6f4f337f608

Changed in qemu (Ubuntu):
assignee: Christian Ehrhardt  (paelzer) → nobody
Thomas Huth (th-huth)
Changed in qemu:
status: Fix Committed → Fix Released
Revision history for this message
Timo Aaltonen (tjaalton) wrote : Please test proposed package

Hello Nelson, or anyone else affected,

Accepted qemu into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/qemu/1:4.2-3ubuntu6.5 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Changed in qemu (Ubuntu Focal):
status: Triaged → Fix Committed
tags: added: verification-needed verification-needed-focal
Revision history for this message
Ubuntu SRU Bot (ubuntu-sru-bot) wrote : Autopkgtest regression report (qemu/1:4.2-3ubuntu6.5)

All autopkgtests for the newly accepted qemu (1:4.2-3ubuntu6.5) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

ubuntu-image/1.9+20.04ubuntu1 (amd64)
systemd/245.4-4ubuntu3.2 (amd64, armhf, s390x, ppc64el)
livecd-rootfs/2.664.4 (amd64, arm64, s390x, ppc64el)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/focal/update_excuses.html#qemu

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

Revision history for this message
Christian Ehrhardt  (paelzer) wrote :

old version
sudo apt install qemu-system-s390x=1:4.2-3ubuntu6.4
...test as listed in the test instructions ...

ubuntu@focal-sqxbr:~$ ./a.out
Segmentation fault
(qemu is dead at this point)

$ sudo apt install qemu-system-s390x=1:4.2-3ubuntu6.5
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
  qemu-system-s390x
1 upgraded, 0 newly installed, 0 to remove and 315 not upgraded.
Need to get 2334 kB of archives.
After this operation, 4096 B of additional disk space will be used.
Get:1 http://ports.ubuntu.com focal-proposed/main s390x qemu-system-s390x s390x 1:4.2-3ubuntu6.5 [2334 kB]
Fetched 2334 kB in 1s (3927 kB/s)
(Reading database ... 203254 files and directories currently installed.)
Preparing to unpack .../qemu-system-s390x_1%3a4.2-3ubuntu6.5_s390x.deb ...
Unpacking qemu-system-s390x (1:4.2-3ubuntu6.5) over (1:4.2-3ubuntu6.4) ...
Setting up qemu-system-s390x (1:4.2-3ubuntu6.5) ...
Processing triggers for man-db (2.9.3-2) ...
ubuntu@s1lp05:~$

ubuntu@focal-sqxbr:~$ ./a.out
(no crash)

Setting verified

tags: added: verification-done verification-done-focal
removed: verification-needed verification-needed-focal
Revision history for this message
Chris Halse Rogers (raof) wrote : Update Released

The verification of the Stable Release Update for qemu has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package qemu - 1:4.2-3ubuntu6.5

---------------
qemu (1:4.2-3ubuntu6.5) focal; urgency=medium

  * further stabilize qemu by importing patches of qemu v4.2.1
    Fixes (LP: #1891203) and (LP: #1891877)
    - d/p/stable/lp-1891877-*
    - as part of the stabilization this also fixes an
      riscv emulation issue due to the CVE-2020-13754 fixes via
      d/p/ubuntu/hw-riscv-Allow-64-bit-access-to-SiFive-CLINT.patch
  * fix s390x SQXBR emulation (LP: #1883984)
    - d/p/ubuntu/lp-1883984-target-s390x-Fix-SQXBR.patch
  * fix -no-reboot for s390x protvirt guests (LP: #1890154)
    - d/p/ubuntu/lp-1890154-s390x-protvirt-allow-to-IPL-secure-guests-with-*

 -- Christian Ehrhardt <email address hidden> Wed, 19 Aug 2020 13:40:49 +0200

Changed in qemu (Ubuntu Focal):
status: Fix Committed → Fix Released
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