syzbot

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BUG: KASAN: slab-use-after-free in iov_iter_folioq_advance lib/iov_iter.c:540 [inline]
BUG: KASAN: slab-use-after-free in iov_iter_advance+0x677/0x6c0 lib/iov_iter.c:576
Read of size 8 at addr ffff8880237c0d20 by task syz.2.17/5503

CPU: 0 UID: 0 PID: 5503 Comm: syz.2.17 Not tainted 6.11.0-syzkaller-03917-ga940d9a43e62 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 iov_iter_folioq_advance lib/iov_iter.c:540 [inline]
 iov_iter_advance+0x677/0x6c0 lib/iov_iter.c:576
 netfs_write_folio+0x745/0x18f0 fs/netfs/write_issue.c:481
 netfs_writepages+0x2ba/0xb90 fs/netfs/write_issue.c:541
 do_writepages+0x1a3/0x7f0 mm/page-writeback.c:2683
 filemap_fdatawrite_wbc mm/filemap.c:397 [inline]
 filemap_fdatawrite_wbc+0x148/0x1c0 mm/filemap.c:387
 __filemap_fdatawrite_range+0xba/0x100 mm/filemap.c:430
 v9fs_dir_release+0x429/0x590 fs/9p/vfs_dir.c:219
 __fput+0x3f6/0xb60 fs/file_table.c:431
 task_work_run+0x14e/0x250 kernel/task_work.c:228
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xaa3/0x2bb0 kernel/exit.c:882
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1031
 get_signal+0x25fb/0x2770 kernel/signal.c:2917
 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 irqentry_exit_to_user_mode+0x13f/0x280 kernel/entry/common.c:231
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7f580e240397
Code: Unable to access opcode bytes at 0x7f580e24036d.
RSP: 002b:00007f580f1c91a0 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 000000000000000b RCX: 00007f580e37def9
RDX: 00007f580f1c91c0 RSI: 00007f580f1c92f0 RDI: 000000000000000b
RBP: 00007f580e3f0b76 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f580e536058 R15: 00007fffabab0da8
 </TASK>

Allocated by task 5503:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:387
 kmalloc_noprof include/linux/slab.h:690 [inline]
 netfs_buffer_append_folio+0x181/0x750 fs/netfs/misc.c:25
 netfs_write_folio+0x542/0x18f0 fs/netfs/write_issue.c:421
 netfs_writepages+0x2ba/0xb90 fs/netfs/write_issue.c:541
 do_writepages+0x1a3/0x7f0 mm/page-writeback.c:2683
 filemap_fdatawrite_wbc mm/filemap.c:397 [inline]
 filemap_fdatawrite_wbc+0x148/0x1c0 mm/filemap.c:387
 __filemap_fdatawrite_range+0xba/0x100 mm/filemap.c:430
 v9fs_dir_release+0x429/0x590 fs/9p/vfs_dir.c:219
 __fput+0x3f6/0xb60 fs/file_table.c:431
 task_work_run+0x14e/0x250 kernel/task_work.c:228
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xaa3/0x2bb0 kernel/exit.c:882
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1031
 get_signal+0x25fb/0x2770 kernel/signal.c:2917
 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 irqentry_exit_to_user_mode+0x13f/0x280 kernel/entry/common.c:231
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

Freed by task 1111:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
 poison_slab_object+0xf7/0x160 mm/kasan/common.c:240
 __kasan_slab_free+0x32/0x50 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2250 [inline]
 slab_free mm/slub.c:4474 [inline]
 kfree+0x12a/0x3b0 mm/slub.c:4595
 netfs_delete_buffer_head+0xa6/0x100 fs/netfs/misc.c:59
 netfs_writeback_unlock_folios fs/netfs/write_collect.c:139 [inline]
 netfs_collect_write_results fs/netfs/write_collect.c:493 [inline]
 netfs_write_collection_worker+0x20f9/0x4f80 fs/netfs/write_collect.c:551
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3393
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff8880237c0c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 288 bytes inside of
 freed 512-byte region [ffff8880237c0c00, ffff8880237c0e00)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x237c0
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xfdffffff(slab)
raw: 00fff00000000040 ffff88801ac42c80 ffffea00008bdc00 dead000000000002
raw: 0000000000000000 0000000000100010 00000001fdffffff 0000000000000000
head: 00fff00000000040 ffff88801ac42c80 ffffea00008bdc00 dead000000000002
head: 0000000000000000 0000000000100010 00000001fdffffff 0000000000000000
head: 00fff00000000002 ffffea00008df001 ffffffffffffffff 0000000000000000
head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4835, tgid 4835 (udevd), ts 20373772704, free_ts 19690893596
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1500
 prep_new_page mm/page_alloc.c:1508 [inline]
 get_page_from_freelist+0x1351/0x2e50 mm/page_alloc.c:3446
 __alloc_pages_noprof+0x22b/0x2460 mm/page_alloc.c:4702
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x4e/0xf0 mm/slub.c:2319
 allocate_slab mm/slub.c:2482 [inline]
 new_slab+0x84/0x260 mm/slub.c:2535
 ___slab_alloc+0xdac/0x1870 mm/slub.c:3721
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3811
 __slab_alloc_node mm/slub.c:3864 [inline]
 slab_alloc_node mm/slub.c:4026 [inline]
 __kmalloc_cache_noprof+0x2b4/0x300 mm/slub.c:4185
 kmalloc_noprof include/linux/slab.h:690 [inline]
 kzalloc_noprof include/linux/slab.h:816 [inline]
 kernfs_fop_open+0x28b/0xdb0 fs/kernfs/file.c:623
 do_dentry_open+0x6ca/0x1530 fs/open.c:958
 vfs_open+0x82/0x3f0 fs/open.c:1088
 do_open fs/namei.c:3774 [inline]
 path_openat+0x1e6a/0x2d60 fs/namei.c:3933
 do_filp_open+0x1dc/0x430 fs/namei.c:3960
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1415
 do_sys_open fs/open.c:1430 [inline]
 __do_sys_openat fs/open.c:1446 [inline]
 __se_sys_openat fs/open.c:1441 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1441
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
page last free pid 4845 tgid 4845 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1101 [inline]
 free_unref_page+0x64a/0xe40 mm/page_alloc.c:2619
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4e/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x192/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:322
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3989 [inline]
 slab_alloc_node mm/slub.c:4038 [inline]
 kmem_cache_alloc_lru_noprof+0x121/0x2f0 mm/slub.c:4057
 alloc_inode+0xba/0x230 fs/inode.c:265
 iget_locked+0x2ee/0x970 fs/inode.c:1424
 kernfs_get_inode+0x48/0x460 fs/kernfs/inode.c:251
 kernfs_iop_lookup+0x1ec/0x330 fs/kernfs/dir.c:1214
 __lookup_slow+0x24f/0x460 fs/namei.c:1732
 lookup_slow fs/namei.c:1749 [inline]
 walk_component+0x350/0x5b0 fs/namei.c:2053
 lookup_last fs/namei.c:2556 [inline]
 path_lookupat+0x17f/0x770 fs/namei.c:2580
 filename_lookup+0x1e5/0x5b0 fs/namei.c:2609
 vfs_statx+0x11e/0x1e0 fs/stat.c:312
 vfs_fstatat+0x9f/0x160 fs/stat.c:341
 __do_sys_newfstatat+0xa2/0x130 fs/stat.c:505

Memory state around the buggy address:
 ffff8880237c0c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880237c0c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880237c0d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8880237c0d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880237c0e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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