I'm glad to see that commit: c9bfb460c3e4 c9bfb460c3e4da2462e16b0f0b200990b36b1dd2 "s390/perf: obtain sie_block from the right address" is tagged (upstream) for stable updates with: Cc: sta...@vger.kernel.org
With that, this commit will automatically be picked up by the Ubuntu kernel teams "Focal update: v5.4.xxx upstream stable release" process. This hasn't happened yet with the latest ticket: "Focal update: v5.4.191 upstream stable release" - LP#1976116 but will be soon. This LP bug will be used for tracking the status. ** Tags added: tracking-upstream-stable ** Changed in: linux (Ubuntu) Importance: Undecided => High ** Tags removed: tracking-upstream-stable ** Tags added: upstream-stable -- 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/1977962 Title: [UBUNTU 21.10] s390/perf: obtain sie_block from the right address Status in Ubuntu on IBM z Systems: New Status in linux package in Ubuntu: New Bug description: Description: s390/perf: obtain sie_block from the right address Symptom: Read from unitialized stack memory, incorrect guest perf data reported, possibly system crash. Problem: When perf is instructed to record a software-based event and to trace the guest, i.e. using the following command: perf kvm --guest --guestvmlinux=endless.elf top -e cpu-clock The reported guest instruction pointer is inaccurate or the system may crash. This is caused by the sie_block being taken from empty1[0] in sie_block() in arch/s390/kernel/perf_event.c, but since 1179f170b6f0 ("s390: fix fpu restore in entry.S") it resides at empty1[1]. Solution: Obtain sie_block from the right address in sie_block(). Reproduction: 1. Start a KVM guest executing an endless loop. 2. Determine the instruction address of the loop. 3. Start perf recording for any software event and trace the guest, for example using this command: perf kvm --guest --guestvmlinux=endless.elf top -e cpu-clock 4. The reported guest instruction addresses don't match the loop's instruction address or the system crashes. Upstream-ID: c9bfb460c3e4da2462e16b0f0b200990b36b1dd2 BBPF Probl.ID: 198450 Preventive: yes Reported: - SupportTicket: - Reference: - Date: 2022-06-02 Author: n...@linux.ibm.com Component: kernel Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c9bfb460c3e4da2462e16b0f0b200990b36b1dd2 Problem occurs / affects impish and jammy To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1977962/+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
