From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f205.google.com (mail-oi1-f205.google.com [209.85.167.205]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4D90439E19A for ; Tue, 30 Jun 2026 20:10:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.205 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782850229; cv=none; b=qwaEzwZ7VZk7+77nzQLkQXrQkwLdjmVJfZ20f/SPuYcq3MM8lBRvqad9TPY4Qq6bA6C22Pheebyk4DL9EfpplJhLVaswanR7rgF5n5+Z4YywFHYhJ5CAmUliIMuFwfE/vca61O0qPgxLMwbh/1oTHGK3A+8HB7OGcEiIXJGPovs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782850229; c=relaxed/simple; bh=ERr+1tk1uPRrobaMFGfJ/Q1xkES2hUiXZ6Zmeni1OxM=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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5614622812f47-495fd99688amr1265977b6e.34.1782850227422; Tue, 30 Jun 2026 13:10:27 -0700 (PDT) Date: Tue, 30 Jun 2026 13:10:27 -0700 In-Reply-To: <6a426dd2.854d4ab9.360e1d.0008.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a4422b3.35583610.9b6d.0002.GAE@google.com> Subject: Re: [syzbot] [kvm-x86?] KASAN: use-after-free Read in kvm_setup_guest_pvclock From: syzbot To: bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, pbonzini@redhat.com, seanjc@google.com, syzkaller-bugs@googlegroups.com, tglx@kernel.org, x86@kernel.org Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 7de6ae9e1220 Add linux-next specific files for 20260629 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=163d19de580000 kernel config: https://syzkaller.appspot.com/x/.config?x=93f99737ecde604c dashboard link: https://syzkaller.appspot.com/bug?extid=fb7c2dd166d3ea63df2a compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1309af41580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f28bae580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/a09187a6eb8d/disk-7de6ae9e.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/f0a76dd86b32/vmlinux-7de6ae9e.xz kernel image: https://storage.googleapis.com/syzbot-assets/864b9d8296e7/bzImage-7de6ae9e.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+fb7c2dd166d3ea63df2a@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in kvm_setup_guest_pvclock+0x439/0x620 arch/x86/kvm/x86.c:1728 Read of size 4 at addr ffff88804d02c320 by task syz.1.180/6591 CPU: 1 UID: 0 PID: 6591 Comm: syz.1.180 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 kvm_setup_guest_pvclock+0x439/0x620 arch/x86/kvm/x86.c:1728 kvm_guest_time_update+0xa32/0xe60 arch/x86/kvm/x86.c:1864 vcpu_enter_guest arch/x86/kvm/x86.c:8038 [inline] vcpu_run+0x150d/0x73e0 arch/x86/kvm/x86.c:8596 kvm_arch_vcpu_ioctl_run+0xe51/0x1960 arch/x86/kvm/x86.c:8929 kvm_vcpu_ioctl+0xa64/0xfe0 virt/kvm/kvm_main.c:4470 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbebb04ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fbeba68d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fbebb2c6090 RCX: 00007fbebb04ce59 RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005 RBP: 00007fbebb0e2e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbebb2c6128 R14: 00007fbebb2c6090 R15: 00007ffefb5754e8 The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x200000000 pfn:0x4d02c flags: 0x80000000000000(node=0|zone=1) raw: 0080000000000000 ffffea000159c008 ffff8880b8642f70 0000000000000000 raw: 0000000200000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO|__GFP_COMP), pid 6589, tgid 6589 (syz.1.180), ts 149074813359 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1861 prep_new_page mm/page_alloc.c:1869 [inline] get_page_from_freelist+0x264c/0x26c0 mm/page_alloc.c:3949 __alloc_frozen_pages_noprof+0x1a6/0x390 mm/page_alloc.c:5322 alloc_pages_mpol+0xce/0x280 mm/mempolicy.c:2490 folio_alloc_mpol_noprof+0x3b/0x1e0 mm/mempolicy.c:2509 vma_alloc_folio_noprof+0xe1/0x1e0 mm/mempolicy.c:2544 folio_prealloc mm/memory.c:-1 [inline] alloc_anon_folio mm/memory.c:5247 [inline] do_anonymous_page mm/memory.c:5342 [inline] do_pte_missing+0x835/0x28f0 mm/memory.c:4564 handle_pte_fault mm/memory.c:6379 [inline] __handle_mm_fault mm/memory.c:6517 [inline] handle_mm_fault+0xe0b/0x1520 mm/memory.c:6686 do_user_addr_fault+0xa4d/0x1340 arch/x86/mm/fault.c:1343 handle_page_fault arch/x86/mm/fault.c:1483 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 page last free pid 6590 tgid 6589 ts 149102566230 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1408 [inline] __free_frozen_pages+0x10de/0x11c0 mm/page_alloc.c:2952 __folio_put+0x30f/0x3c0 mm/swap.c:112 hva_to_pfn_retry virt/kvm/pfncache.c:246 [inline] __kvm_gpc_refresh+0x1277/0x1710 virt/kvm/pfncache.c:330 __kvm_gpc_activate+0x289/0x3b0 virt/kvm/pfncache.c:424 kvm_xen_vcpu_set_attr+0x1d3/0x1190 arch/x86/kvm/xen.c:938 kvm_arch_vcpu_ioctl+0x1467/0x23f0 arch/x86/kvm/x86.c:3815 kvm_vcpu_ioctl+0x7e6/0xfe0 virt/kvm/kvm_main.c:4647 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88804d02c200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88804d02c280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88804d02c300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88804d02c380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88804d02c400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.