[syzbot] [afs?] KASAN: slab-use-after-free Read in __radix_tree_replace

[syzbot <syzbot+8d4b939fcb6c6acbfe97@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    d358e5254674 Merge tag 'for-6.19/dm-changes' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10650592580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=37bf6cac94c6b2f8
dashboard link: https://syzkaller.appspot.com/bug?extid=8d4b939fcb6c6acbfe97
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d358e525.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74b71d0845ac/vmlinux-d358e525.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7b362bbbe01b/bzImage-d358e525.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8d4b939fcb6c6acbfe97@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in replace_slot lib/radix-tree.c:827 [inline]
BUG: KASAN: slab-use-after-free in __radix_tree_replace+0x317/0x360 lib/radix-tree.c:890
Read of size 1 at addr ffff88804f6939c2 by task syz.0.1096/11903

CPU: 2 UID: 0 PID: 11903 Comm: syz.0.1096 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 replace_slot lib/radix-tree.c:827 [inline]
 __radix_tree_replace+0x317/0x360 lib/radix-tree.c:890
 idr_alloc_u32+0x1fd/0x2f0 lib/idr.c:52
 idr_alloc_cyclic+0x10b/0x230 lib/idr.c:125
 afs_alloc_cell fs/afs/cell.c:209 [inline]
 afs_lookup_cell+0x11d1/0x1900 fs/afs/cell.c:278
 afs_parse_source fs/afs/super.c:292 [inline]
 afs_parse_param+0x5c4/0x970 fs/afs/super.c:330
 vfs_parse_fs_param+0x20b/0x3c0 fs/fs_context.c:146
 vfs_fsconfig_locked fs/fsopen.c:303 [inline]
 __do_sys_fsconfig+0x930/0xbe0 fs/fsopen.c:473
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7f84579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f4bd555c EFLAGS: 00000296 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 000000000000000d RCX: 0000000000000001
RDX: 0000000080000000 RSI: 0000000080000180 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 11898:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 unpoison_slab_object mm/kasan/common.c:339 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:365
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x25e/0x770 mm/slub.c:5270
 radix_tree_node_alloc.constprop.0+0x7c/0x350 lib/radix-tree.c:276
 idr_get_free+0x528/0xa30 lib/radix-tree.c:1506
 idr_alloc_u32+0x190/0x2f0 lib/idr.c:46
 idr_alloc_cyclic+0x10b/0x230 lib/idr.c:125
 afs_alloc_cell fs/afs/cell.c:209 [inline]
 afs_lookup_cell+0x11d1/0x1900 fs/afs/cell.c:278
 afs_parse_source fs/afs/super.c:292 [inline]
 afs_parse_param+0x5c4/0x970 fs/afs/super.c:330
 vfs_parse_fs_param+0x20b/0x3c0 fs/fs_context.c:146
 vfs_fsconfig_locked fs/fsopen.c:303 [inline]
 __do_sys_fsconfig+0x930/0xbe0 fs/fsopen.c:473
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Freed by task 0:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6668 [inline]
 kmem_cache_free+0x2d8/0x770 mm/slub.c:6779
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0x79c/0x15f0 kernel/rcu/tree.c:2857
 handle_softirqs+0x219/0x950 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x109/0x170 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

Last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 __call_rcu_common.constprop.0+0xa5/0xa10 kernel/rcu/tree.c:3119
 radix_tree_node_free lib/radix-tree.c:310 [inline]
 delete_node+0x1fc/0x8d0 lib/radix-tree.c:573
 __radix_tree_delete+0x193/0x3d0 lib/radix-tree.c:1379
 radix_tree_delete_item+0xea/0x230 lib/radix-tree.c:1430
 afs_cell_destroy+0x1db/0x310 fs/afs/cell.c:580
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0x79c/0x15f0 kernel/rcu/tree.c:2857
 handle_softirqs+0x219/0x950 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x109/0x170 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

The buggy address belongs to the object at ffff88804f6939c0
 which belongs to the cache radix_tree_node of size 576
The buggy address is located 2 bytes inside of
 freed 576-byte region [ffff88804f6939c0, ffff88804f693c00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4f690
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88804d3b9e01
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801b44cc80 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080170017 00000000f5000000 ffff88804d3b9e01
head: 04fff00000000040 ffff88801b44cc80 dead000000000122 0000000000000000
head: 0000000000000000 0000000080170017 00000000f5000000 ffff88804d3b9e01
head: 04fff00000000002 ffffea00013da401 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Reclaimable, gfp_mask 0x152810(GFP_NOWAIT|__GFP_RECLAIMABLE|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 11848, tgid 11847 (syz.2.1089), ts 643758920019, free_ts 199291394557
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1af/0x220 mm/page_alloc.c:1846
 prep_new_page mm/page_alloc.c:1854 [inline]
 get_page_from_freelist+0xd0b/0x31a0 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x25f/0x2430 mm/page_alloc.c:5210
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab mm/slub.c:3248 [inline]
 new_slab+0x2c3/0x430 mm/slub.c:3302
 ___slab_alloc+0xe18/0x1c90 mm/slub.c:4656
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 kmem_cache_alloc_lru_noprof+0x451/0x770 mm/slub.c:5282
 xas_alloc+0x34f/0x460 lib/xarray.c:378
 xas_create+0x72b/0x1460 lib/xarray.c:685
 xas_store+0x90/0x1910 lib/xarray.c:795
 shmem_add_to_page_cache+0x7b7/0xa70 mm/shmem.c:922
 shmem_alloc_and_add_folio+0x662/0xc20 mm/shmem.c:1958
 shmem_get_folio_gfp+0x67f/0x1610 mm/shmem.c:2556
 shmem_fault+0x1fe/0xa00 mm/shmem.c:2757
 __do_fault+0x10d/0x490 mm/memory.c:5320
page last free pid 7671 tgid 7671 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0x7df/0x1170 mm/page_alloc.c:2943
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4c/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:349
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x25e/0x770 mm/slub.c:5270
 getname_flags.part.0+0x4c/0x550 fs/namei.c:146
 getname_flags+0x93/0xf0 include/linux/audit.h:345
 getname include/linux/fs.h:2498 [inline]
 getname_maybe_null include/linux/fs.h:2505 [inline]
 getname_maybe_null include/linux/fs.h:2502 [inline]
 vfs_fstatat+0xe1/0xf0 fs/stat.c:370
 __do_sys_newfstatat+0x97/0x120 fs/stat.c:542
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88804f693880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88804f693900: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff88804f693980: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
                                           ^
 ffff88804f693a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88804f693a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi


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