kafs: addr_prefs: Invalid Command
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BUG: KASAN: slab-out-of-bounds in afs_split_string fs/afs/addr_prefs.c:51 [inline]
BUG: KASAN: slab-out-of-bounds in afs_proc_addr_prefs_write+0x13a9/0x15f0 fs/afs/addr_prefs.c:415
Read of size 1 at addr ffff88814c8f865b by task syz.0.116/6520

CPU: 0 UID: 0 PID: 6520 Comm: syz.0.116 Tainted: G     U              6.15.0-rc5-syzkaller-00207-g1a33418a69cc #0 PREEMPT(full) 
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 afs_split_string fs/afs/addr_prefs.c:51 [inline]
 afs_proc_addr_prefs_write+0x13a9/0x15f0 fs/afs/addr_prefs.c:415
 proc_simple_write+0x114/0x1b0 fs/proc/generic.c:825
 pde_write fs/proc/inode.c:330 [inline]
 proc_reg_write+0x23d/0x330 fs/proc/inode.c:342
 vfs_write+0x25c/0x1180 fs/read_write.c:682
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f858ef8e969
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:00007f858fe27038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f858f1b5fa0 RCX: 00007f858ef8e969
RDX: 000000000000005a RSI: 00002000000002c0 RDI: 0000000000000003
RBP: 00007f858f010ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f858f1b5fa0 R15: 00007ffeb27831b8
 </TASK>

Allocated by task 6520:
 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:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_node_track_caller_noprof+0x221/0x510 mm/slub.c:4346
 memdup_user_nul+0x2b/0x120 mm/util.c:302
 proc_simple_write+0xc7/0x1b0 fs/proc/generic.c:822
 pde_write fs/proc/inode.c:330 [inline]
 proc_reg_write+0x23d/0x330 fs/proc/inode.c:342
 vfs_write+0x25c/0x1180 fs/read_write.c:682
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88814c8f8600
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes to the right of
 allocated 91-byte region [ffff88814c8f8600, ffff88814c8f865b)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14c8f8
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000000 ffff88801b441280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080200020 00000000f5000000 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 0x252800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 6503, tgid 6502 (syz.2.113), ts 159972572488, free_ts 153937063589
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x135c/0x3920 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x263/0x23a0 mm/page_alloc.c:4970
 alloc_slab_page mm/slub.c:2452 [inline]
 allocate_slab mm/slub.c:2618 [inline]
 new_slab+0x94/0x340 mm/slub.c:2672
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3858
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3948
 __slab_alloc_node mm/slub.c:4023 [inline]
 slab_alloc_node mm/slub.c:4184 [inline]
 __kmalloc_cache_node_noprof+0x100/0x420 mm/slub.c:4366
 kmalloc_node_noprof include/linux/slab.h:928 [inline]
 alloc_node_nr_active kernel/workqueue.c:4872 [inline]
 __alloc_workqueue+0x506/0x1810 kernel/workqueue.c:5726
 alloc_workqueue+0xd2/0x200 kernel/workqueue.c:5786
 tipc_topsrv_work_start net/tipc/topsrv.c:635 [inline]
 tipc_topsrv_start net/tipc/topsrv.c:679 [inline]
 tipc_topsrv_init_net+0x423/0x9e0 net/tipc/topsrv.c:725
 ops_init+0x1df/0x5f0 net/core/net_namespace.c:138
 setup_net+0x21e/0x850 net/core/net_namespace.c:364
 copy_net_ns+0x2a6/0x5f0 net/core/net_namespace.c:518
 create_new_namespaces+0x3ea/0xad0 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:228
 ksys_unshare+0x45b/0xa40 kernel/fork.c:3375
page last free pid 6316 tgid 6311 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0x69d/0xff0 mm/page_alloc.c:2725
 kasan_depopulate_vmalloc_pte+0x63/0x80 mm/kasan/shadow.c:408
 apply_to_pte_range mm/memory.c:2941 [inline]
 apply_to_pmd_range mm/memory.c:2985 [inline]
 apply_to_pud_range mm/memory.c:3021 [inline]
 apply_to_p4d_range mm/memory.c:3057 [inline]
 __apply_to_page_range+0x617/0xd60 mm/memory.c:3093
 kasan_release_vmalloc+0xd1/0xe0 mm/kasan/shadow.c:529
 kasan_release_vmalloc_node mm/vmalloc.c:2196 [inline]
 purge_vmap_node+0x1cb/0xa70 mm/vmalloc.c:2213
 __purge_vmap_area_lazy+0x9d1/0xc90 mm/vmalloc.c:2304
 _vm_unmap_aliases+0x43b/0x670 mm/vmalloc.c:2899
 change_page_attr_set_clr+0x252/0x4a0 arch/x86/mm/pat/set_memory.c:2085
 set_memory_rox+0xbd/0x110 arch/x86/mm/pat/set_memory.c:2317
 machine_kexec_prepare+0x9fe/0xf90 arch/x86/kernel/machine_kexec_64.c:326
 do_kexec_load+0x664/0x8d0 kernel/kexec.c:142
 __do_sys_kexec_load kernel/kexec.c:261 [inline]
 __se_sys_kexec_load kernel/kexec.c:242 [inline]
 __x64_sys_kexec_load+0x1bf/0x230 kernel/kexec.c:242
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88814c8f8500: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
 ffff88814c8f8580: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff88814c8f8600: 00 00 00 00 00 00 00 00 00 00 00 03 fc fc fc fc
                                                    ^
 ffff88814c8f8680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88814c8f8700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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