[syzbot] [kvm-x86?] KASAN: use-after-free Read in kvm_setup_guest_pvclock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dc59e4fea9d8 Linux 7.2-rc1
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16f1b46e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=77808e35144e725c
dashboard link: https://syzkaller.appspot.com/bug?extid=fb7c2dd166d3ea63df2a
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9911e5707540/disk-dc59e4fe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bb0af0bc6e42/vmlinux-dc59e4fe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b7ca0661e875/bzImage-dc59e4fe.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fb7c2d...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in kvm_setup_guest_pvclock+0x5bf/0x660 arch/x86/kvm/x86.c:3272
Read of size 4 at addr ffff88804c505320 by task syz.1.5312/25543

CPU: 1 UID: 0 PID: 25543 Comm: syz.1.5312 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
kvm_setup_guest_pvclock+0x5bf/0x660 arch/x86/kvm/x86.c:3272
kvm_guest_time_update+0xa11/0x10b0 arch/x86/kvm/x86.c:3408
vcpu_enter_guest arch/x86/kvm/x86.c:11149 [inline]
vcpu_run+0x1cf1/0x5d50 arch/x86/kvm/x86.c:11707
kvm_arch_vcpu_ioctl_run+0x5b6/0x1890 arch/x86/kvm/x86.c:12062
kvm_vcpu_ioctl+0x730/0x1700 virt/kvm/kvm_main.c:4470
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5deff9ce59
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:00007f5df0dd3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5df0216090 RCX: 00007f5deff9ce59
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007f5df0032e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5df0216128 R14: 00007f5df0216090 R15: 00007ffd2f6378e8
</TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x200000000 pfn:0x4c505
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea000145ba48 ffff8880b85414b0 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 25531, tgid 25531 (syz.1.5312), ts 1799784670966, free_ts 1801394089155
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
folio_alloc_mpol_noprof+0x36/0x260 mm/mempolicy.c:2509
vma_alloc_folio_noprof+0xed/0x1d0 mm/mempolicy.c:2544
folio_prealloc mm/memory.c:1207 [inline]
alloc_anon_folio mm/memory.c:5247 [inline]
do_anonymous_page+0xb2b/0x2080 mm/memory.c:5342
do_pte_missing mm/memory.c:4564 [inline]
handle_pte_fault mm/memory.c:6379 [inline]
__handle_mm_fault+0x1d2c/0x2a00 mm/memory.c:6517
handle_mm_fault+0x37b/0xa30 mm/memory.c:6686
do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1343
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
page last free pid 25532 tgid 25531 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
__folio_put+0x3b4/0x5f0 mm/swap.c:112
folio_put include/linux/mm.h:2124 [inline]
put_page include/linux/mm.h:2193 [inline]
kvm_release_page_clean virt/kvm/kvm_main.c:2813 [inline]
kvm_release_page_clean+0x1dc/0x250 virt/kvm/kvm_main.c:2807
hva_to_pfn_retry virt/kvm/pfncache.c:246 [inline]
__kvm_gpc_refresh+0x1a63/0x22d0 virt/kvm/pfncache.c:330
__kvm_gpc_activate+0x2ab/0x490 virt/kvm/pfncache.c:424
kvm_gpc_activate_hva+0x73/0xa0 virt/kvm/pfncache.c:444
kvm_xen_vcpu_set_attr+0xfa0/0x1350 arch/x86/kvm/xen.c:938
kvm_arch_vcpu_ioctl+0xf98/0x5730 arch/x86/kvm/x86.c:6612
kvm_vcpu_ioctl+0x8a0/0x1700 virt/kvm/kvm_main.c:4647
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88804c505200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88804c505280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88804c505300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88804c505380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88804c505400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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