==================================================================
BUG: KASAN: stack-out-of-bounds in __cpa_flush_tlb+0x46/0x270 arch/x86/mm/pat/set_memory.c:407
Read of size 8 at addr ffffc9000b77fc20 by task syz.4.5/5998

CPU: 0 UID: 0 PID: 5998 Comm: syz.4.5 Not tainted 6.16.0-rc4-next-20250630-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 __cpa_flush_tlb+0x46/0x270 arch/x86/mm/pat/set_memory.c:407
 csd_do_func kernel/smp.c:134 [inline]
 __flush_smp_call_function_queue+0x370/0xaa0 kernel/smp.c:540
 __sysvec_call_function_single+0xa8/0x3d0 arch/x86/kernel/smp.c:271
 instr_sysvec_call_function_single arch/x86/kernel/smp.c:266 [inline]
 sysvec_call_function_single+0x9e/0xc0 arch/x86/kernel/smp.c:266
 </IRQ>
 <TASK>
 asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:709
RIP: 0010:finish_task_switch+0x26b/0x950 kernel/sched/core.c:5181
Code: 0f 84 3c 01 00 00 48 85 db 0f 85 63 01 00 00 e9 27 05 00 00 4c 8b 75 d0 4c 89 e7 e8 2f db e0 09 e8 3a 0e 36 00 fb 4c 8b 65 c0 <49> 8d bc 24 18 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90005547238 EFLAGS: 00000282
RAX: baa4d2ddbd178000 RBX: 0000000000000000 RCX: baa4d2ddbd178000
RDX: 0000000000000000 RSI: ffffffff8d992cd0 RDI: ffffffff8be31d00
RBP: ffffc90005547290 R08: ffffffff8fa17437 R09: 1ffffffff1f42e86
R10: dffffc0000000000 R11: fffffbfff1f42e87 R12: ffff88807b248000
R13: dffffc0000000000 R14: ffff88802fe11e00 R15: 0000000000000000
 context_switch kernel/sched/core.c:5316 [inline]
 __schedule+0x16fd/0x4d00 kernel/sched/core.c:6696
 __schedule_loop kernel/sched/core.c:6774 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6789
 schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
 unix_wait_for_peer+0x1e9/0x2e0 net/unix/af_unix.c:1591
 unix_dgram_sendmsg+0xb1f/0x1870 net/unix/af_unix.c:2194
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:729
 ____sys_sendmsg+0x52d/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmmsg+0x227/0x430 net/socket.c:2757
 __do_sys_sendmmsg net/socket.c:2784 [inline]
 __se_sys_sendmmsg net/socket.c:2781 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2781
 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: 0033:0x7f33bbf8e929
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:00007f33bcde1038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f33bc1b6080 RCX: 00007f33bbf8e929
RDX: 0000000000000651 RSI: 0000200000000000 RDI: 0000000000000007
RBP: 00007f33bc010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f33bc1b6080 R15: 00007ffe2226c9f8
 </TASK>

The buggy address belongs to the virtual mapping at
 [ffffc9000b778000, ffffc9000b781000) created by:
 copy_process+0x54b/0x3c00 kernel/fork.c:1998

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88807859bdc0 pfn:0x7859b
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff88807859bdc0 0000000000000000 00000001ffffffff 0000000000000000
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 5983, tgid 5983 (syz.0.1), ts 85067099723, free_ts 84338185775
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1848
 prep_new_page mm/page_alloc.c:1856 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3855
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5145
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_frozen_pages_noprof mm/mempolicy.c:2490 [inline]
 alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2510
 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:310 [inline]
 dup_task_struct+0x3e7/0x860 kernel/fork.c:876
 copy_process+0x54b/0x3c00 kernel/fork.c:1998
 kernel_clone+0x21e/0x870 kernel/fork.c:2598
 __do_sys_clone3 kernel/fork.c:2902 [inline]
 __se_sys_clone3+0x256/0x2d0 kernel/fork.c:2881
 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
page last free pid 23 tgid 23 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1392 [inline]
 __free_frozen_pages+0xb80/0xd80 mm/page_alloc.c:2892
 rcu_do_batch kernel/rcu/tree.c:2582 [inline]
 rcu_core+0xca8/0x1710 kernel/rcu/tree.c:2838
 handle_softirqs+0x286/0x870 kernel/softirq.c:579
 run_ksoftirqd+0x9b/0x100 kernel/softirq.c:968
 smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffffc9000b77fb00: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
 ffffc9000b77fb80: 00 00 f2 f2 00 f3 f3 f3 00 00 00 00 00 00 00 00
>ffffc9000b77fc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                               ^
 ffffc9000b77fc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000b77fd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
----------------
Code disassembly (best guess):
   0:	0f 84 3c 01 00 00    	je     0x142
   6:	48 85 db             	test   %rbx,%rbx
   9:	0f 85 63 01 00 00    	jne    0x172
   f:	e9 27 05 00 00       	jmp    0x53b
  14:	4c 8b 75 d0          	mov    -0x30(%rbp),%r14
  18:	4c 89 e7             	mov    %r12,%rdi
  1b:	e8 2f db e0 09       	call   0x9e0db4f
  20:	e8 3a 0e 36 00       	call   0x360e5f
  25:	fb                   	sti
  26:	4c 8b 65 c0          	mov    -0x40(%rbp),%r12
* 2a:	49 8d bc 24 18 16 00 	lea    0x1618(%r12),%rdi <-- trapping instruction
  31:	00
  32:	48 89 f8             	mov    %rdi,%rax
  35:	48 c1 e8 03          	shr    $0x3,%rax
  39:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax
  3e:	84 c0                	test   %al,%al