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BUG: KASAN: stack-out-of-bounds in iterate_bvec include/linux/iov_iter.h:116 [inline]
BUG: KASAN: stack-out-of-bounds in __copy_from_iter_mc+0x30a/0x3f0 lib/iov_iter.c:262
Read of size 4 at addr ffffc900154bf594 by task syz-executor.3/5952

CPU: 1 PID: 5952 Comm: syz-executor.3 Not tainted 6.6.0-rc3-next-20230929-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xc4/0x620 mm/kasan/report.c:475
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 iterate_bvec include/linux/iov_iter.h:116 [inline]
 __copy_from_iter_mc+0x30a/0x3f0 lib/iov_iter.c:262
 __copy_from_iter lib/iov_iter.c:271 [inline]
 copy_page_from_iter_atomic+0x471/0x11e0 lib/iov_iter.c:504
 generic_perform_write+0x2e9/0x600 mm/filemap.c:3964
 ext4_buffered_write_iter+0x11f/0x3c0 fs/ext4/file.c:299
 ext4_file_write_iter+0x7f7/0x1860 fs/ext4/file.c:717
 __kernel_write_iter+0x261/0x7e0 fs/read_write.c:517
 dump_emit_page fs/coredump.c:888 [inline]
 dump_user_range+0x299/0x790 fs/coredump.c:915
 elf_core_dump+0x2700/0x3900 fs/binfmt_elf.c:2142
 do_coredump+0x2c97/0x3fc0 fs/coredump.c:764
 get_signal+0x2434/0x2790 kernel/signal.c:2890
 arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
 exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
 exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
 irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:309
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0033:0x7f3a76427797
Code: fa 09 00 e8 db fa ff ff 48 8d 3d 81 fa 09 00 e8 cf fa ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 53 89 fb 48 83 ec 10 <64> 8b 04 25 ac ff ff ff 85 c0 74 2a 89 fe 31 c0 bf 3c 00 00 00 e8
RSP: 002b:00007f3a771731e0 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 000000000000000b RCX: 00007f3a7647cae9
RDX: 00007f3a77173200 RSI: 00007f3a77173330 RDI: 000000000000000b
RBP: 00007f3a764c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 000000000000000b R14: 00007f3a7659bf80 R15: 00007ffc2daa6d78
 </TASK>

The buggy address belongs to stack of task syz-executor.3/5952
 and is located at offset 108 in frame:
 dump_user_range+0x0/0x790 fs/coredump.c:482

This frame has 3 objects:
 [48, 56) 'pos'
 [80, 96) 'bvec'
 [112, 152) 'iter'

The buggy address belongs to the virtual mapping at
 [ffffc900154b8000, ffffc900154c1000) created by:
 kernel_clone+0xfd/0x920 kernel/fork.c:2902

The buggy address belongs to the physical page:
page:ffffea0000a15100 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28544
memcg:ffff88801e013382
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff88801e013382
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 2, tgid 2 (kthreadd), ts 282794249180, free_ts 260269716685
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2cf/0x340 mm/page_alloc.c:1534
 prep_new_page mm/page_alloc.c:1541 [inline]
 get_page_from_freelist+0x98f/0x32a0 mm/page_alloc.c:3333
 __alloc_pages+0x1d0/0x4a0 mm/page_alloc.c:4589
 alloc_pages+0x1a9/0x270 mm/mempolicy.c:2304
 vm_area_alloc_pages mm/vmalloc.c:3063 [inline]
 __vmalloc_area_node mm/vmalloc.c:3139 [inline]
 __vmalloc_node_range+0x8f3/0x1bf0 mm/vmalloc.c:3320
 alloc_thread_stack_node kernel/fork.c:309 [inline]
 dup_task_struct kernel/fork.c:1118 [inline]
 copy_process+0x13e3/0x74b0 kernel/fork.c:2327
 kernel_clone+0xfd/0x920 kernel/fork.c:2902
 kernel_thread+0xc0/0x100 kernel/fork.c:2964
 create_kthread kernel/kthread.c:411 [inline]
 kthreadd+0x4fb/0x7d0 kernel/kthread.c:764
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1134 [inline]
 free_unref_page_prepare+0x476/0xa40 mm/page_alloc.c:2383
 free_unref_page+0x33/0x3b0 mm/page_alloc.c:2518
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x18e/0x1d0 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x65/0x90 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook mm/slab.h:762 [inline]
 slab_alloc_node mm/slub.c:3478 [inline]
 __kmem_cache_alloc_node+0x195/0x330 mm/slub.c:3517
 kmalloc_trace+0x25/0xe0 mm/slab_common.c:1095
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 kernfs_iop_get_link fs/kernfs/symlink.c:135 [inline]
 kernfs_iop_get_link+0x65/0x850 fs/kernfs/symlink.c:126
 vfs_readlink+0x1db/0x370 fs/namei.c:5089
 do_readlinkat+0x29b/0x2f0 fs/stat.c:502
 __do_sys_readlink fs/stat.c:523 [inline]
 __se_sys_readlink fs/stat.c:520 [inline]
 __x64_sys_readlink+0x78/0xb0 fs/stat.c:520
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffffc900154bf480: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900154bf500: 00 00 00 00 00 f1 f1 f1 f1 f1 f1 00 f2 f2 f2 00
>ffffc900154bf580: 00 f2 f2 00 00 00 00 00 f3 f3 f3 f3 f3 00 00 00
                         ^
 ffffc900154bf600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900154bf680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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