syzbot

loop4: detected capacity change from 0 to 4096
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BUG: KASAN: stack-out-of-bounds in vsnprintf+0x5f6/0xf00 lib/vsprintf.c:2878
Read of size 8 at addr ffffc90006337718 by task syz.4.519/7161

CPU: 1 UID: 0 PID: 7161 Comm: syz.4.519 Tainted: G        W           6.16.0-syzkaller-08685-g260f6f4fda93 #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
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
 vsnprintf+0x5f6/0xf00 lib/vsprintf.c:2878
 vprintk_store+0x3ef/0xd10 kernel/printk/printk.c:2279
 vprintk_emit+0x224/0x7c0 kernel/printk/printk.c:2426
 vprintk_deferred kernel/printk/printk.c:4602 [inline]
 _printk_deferred+0xdd/0x130 kernel/printk/printk.c:4611
 unwind_next_frame+0x1dc7/0x2390 arch/x86/kernel/unwind_orc.c:667
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_trace+0x49/0x390 kernel/locking/lockdep.c:587
 check_prev_add kernel/locking/lockdep.c:3226 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0x14b0/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 rt_spin_lock+0x88/0x2c0 kernel/locking/spinlock_rt.c:56
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 force_sig_info_to_task+0x6c/0x5a0 kernel/signal.c:1302
 force_sig_info kernel/signal.c:1331 [inline]
 force_sig+0xc9/0x120 kernel/signal.c:1645
 __exc_general_protection arch/x86/kernel/traps.c:822 [inline]
 exc_general_protection+0xdb/0x200 arch/x86/kernel/traps.c:792
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617
 </TASK>

The buggy address belongs to stack of task syz.4.519/7161
internal error: frame has invalid marker: 16140896666449346560

The buggy address belongs to a 8-page vmalloc region starting at 0xffffc90006330000 allocated at copy_process+0x545/0x3ae0 kernel/fork.c:2000
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x276ff
memcg:ffff88814574cf82
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000001ffffffff ffff88814574cf82
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 7160, tgid 7160 (syz.4.519), ts 439305495865, free_ts 439089950538
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x2119/0x21b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2419
 alloc_frozen_pages_noprof mm/mempolicy.c:2490 [inline]
 alloc_pages_noprof+0xcf/0x1e0 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:317 [inline]
 dup_task_struct+0x3e7/0x860 kernel/fork.c:877
 copy_process+0x545/0x3ae0 kernel/fork.c:2000
 kernel_clone+0x224/0x7c0 kernel/fork.c:2599
 __do_sys_clone3 kernel/fork.c:2903 [inline]
 __se_sys_clone3+0x256/0x2d0 kernel/fork.c:2882
 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 6019 tgid 6019 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 free_unref_folios+0xc8b/0x14e0 mm/page_alloc.c:2763
 folios_put_refs+0x569/0x670 mm/swap.c:992
 folio_batch_release include/linux/pagevec.h:101 [inline]
 truncate_inode_pages_range+0x338/0xb90 mm/truncate.c:383
 kill_bdev block/bdev.c:91 [inline]
 blkdev_flush_mapping+0x10b/0x280 block/bdev.c:712
 blkdev_put_whole block/bdev.c:719 [inline]
 bdev_release+0x422/0x660 block/bdev.c:1144
 blkdev_release+0x15/0x20 block/fops.c:699
 __fput+0x45b/0xa80 fs/file_table.c:468
 fput_close_sync+0x119/0x200 fs/file_table.c:573
 __do_sys_close fs/open.c:1587 [inline]
 __se_sys_close fs/open.c:1572 [inline]
 __x64_sys_close+0x7f/0x110 fs/open.c:1572
 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

Memory state around the buggy address:
 ffffc90006337600: f1 f1 f1 f1 04 f2 00 f2 f2 f2 00 f2 f2 f2 00 f2
 ffffc90006337680: f2 f2 04 f3 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90006337700: f1 f1 f1 f1 00 00 00 00 f1 f1 f1 f1 00 00 00 f3
                            ^
 ffffc90006337780: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90006337800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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