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BUG: KASAN: stack-out-of-bounds in user_mode arch/x86/include/asm/ptrace.h:214 [inline]
BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0x1cb0/0x2390 arch/x86/kernel/unwind_orc.c:482
Read of size 2 at addr ffffc900040cf4b0 by task syz.0.365/7948

CPU: 0 UID: 0 PID: 7948 Comm: syz.0.365 Not tainted 6.16.0-syzkaller-11699-g7e161a991ea7 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 user_mode arch/x86/include/asm/ptrace.h:214 [inline]
 unwind_next_frame+0x1cb0/0x2390 arch/x86/kernel/unwind_orc.c:482
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save_tsk+0x15f/0x200 kernel/stacktrace.c:150
 proc_pid_stack+0x12c/0x1f0 fs/proc/base.c:492
 proc_single_show+0xee/0x190 fs/proc/base.c:812
 traverse+0x1e9/0x570 fs/seq_file.c:111
 seq_read_iter+0xcfe/0xe10 fs/seq_file.c:195
 seq_read+0x2e2/0x3d0 fs/seq_file.c:162
 vfs_read+0x200/0x980 fs/read_write.c:570
 ksys_pread64 fs/read_write.c:763 [inline]
 __do_sys_pread64 fs/read_write.c:771 [inline]
 __se_sys_pread64 fs/read_write.c:768 [inline]
 __x64_sys_pread64+0x193/0x220 fs/read_write.c:768
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f348ed8eb69
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f348fb5d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
RAX: ffffffffffffffda RBX: 00007f348efb6080 RCX: 00007f348ed8eb69
RDX: 000000000000000f RSI: 0000200000000140 RDI: 0000000000000004
RBP: 00007f348ee11df1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f348efb6080 R15: 00007ffd8f512108
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888032545500 pfn:0x32545
memcg:ffff888028460082
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff888032545500 0000000000000000 00000001ffffffff ffff888028460082
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 2, tgid 2 (kthreadd), ts 277517250944, free_ts 277304315972
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2507
 vm_area_alloc_pages mm/vmalloc.c:3642 [inline]
 __vmalloc_area_node mm/vmalloc.c:3720 [inline]
 __vmalloc_node_range_noprof+0x97d/0x12f0 mm/vmalloc.c:3893
 __vmalloc_node_noprof+0xc2/0x110 mm/vmalloc.c:3956
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct+0x3e7/0x860 kernel/fork.c:878
 copy_process+0x54b/0x3c00 kernel/fork.c:2001
 kernel_clone+0x21e/0x840 kernel/fork.c:2602
 kernel_thread+0x10c/0x160 kernel/fork.c:2664
 create_kthread kernel/kthread.c:486 [inline]
 kthreadd+0x575/0x770 kernel/kthread.c:846
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 5874 tgid 5874 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861
 handle_softirqs+0x286/0x870 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Memory state around the buggy address:
 ffffc900040cf380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900040cf400: f1 f1 f1 f1 04 f2 00 00 00 f2 f2 f2 f2 f2 00 f2
>ffffc900040cf480: f2 f2 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00
                                     ^
 ffffc900040cf500: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f3 f3 f3
 ffffc900040cf580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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