==================================================================
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+0x123b/0x14e0 fs/afs/addr_prefs.c:415
Read of size 1 at addr ffff88802fd2ec1d by task syz.1.418/6862

CPU: 1 UID: 0 PID: 6862 Comm: syz.1.418 Not tainted 6.13.0-rc2-syzkaller-00159-gf932fb9b4074 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
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+0xc3/0x620 mm/kasan/report.c:489
 kasan_report+0xd9/0x110 mm/kasan/report.c:602
 afs_split_string fs/afs/addr_prefs.c:51 [inline]
 afs_proc_addr_prefs_write+0x123b/0x14e0 fs/afs/addr_prefs.c:415
 proc_simple_write+0x114/0x1b0 fs/proc/generic.c:815
 pde_write fs/proc/inode.c:330 [inline]
 proc_reg_write+0x23d/0x330 fs/proc/inode.c:342
 vfs_write+0x24c/0x1150 fs/read_write.c:677
 ksys_write+0x12b/0x250 fs/read_write.c:731
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1d9cd85d19
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:00007f1d9dbfb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1d9cf75fa0 RCX: 00007f1d9cd85d19
RDX: 000000000000001c RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00007f1d9ce01a20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1d9cf75fa0 R15: 00007ffe10f40238
 </TASK>

Allocated by task 6862:
 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:4283 [inline]
 __kmalloc_node_track_caller_noprof+0x21d/0x520 mm/slub.c:4302
 memdup_user_nul+0x2b/0x110 mm/util.c:305
 proc_simple_write+0xc7/0x1b0 fs/proc/generic.c:812
 pde_write fs/proc/inode.c:330 [inline]
 proc_reg_write+0x23d/0x330 fs/proc/inode.c:342
 vfs_write+0x24c/0x1150 fs/read_write.c:677
 ksys_write+0x12b/0x250 fs/read_write.c:731
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802fd2ec00
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes to the right of
 allocated 29-byte region [ffff88802fd2ec00, ffff88802fd2ec1d)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2fd2e
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801ac41780 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080400040 00000001f5000000 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 0x52800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP), pid 5182, tgid 5182 (hostname), ts 35718472211, free_ts 34050246423
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1556
 prep_new_page mm/page_alloc.c:1564 [inline]
 get_page_from_freelist+0xfce/0x2f80 mm/page_alloc.c:3474
 __alloc_pages_noprof+0x223/0x25b0 mm/page_alloc.c:4751
 alloc_pages_mpol_noprof+0x2c9/0x610 mm/mempolicy.c:2269
 alloc_slab_page mm/slub.c:2408 [inline]
 allocate_slab mm/slub.c:2574 [inline]
 new_slab+0x2c9/0x410 mm/slub.c:2627
 ___slab_alloc+0xce2/0x1650 mm/slub.c:3815
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3905
 __slab_alloc_node mm/slub.c:3980 [inline]
 slab_alloc_node mm/slub.c:4141 [inline]
 __kmalloc_cache_noprof+0xf6/0x420 mm/slub.c:4309
 kmalloc_noprof include/linux/slab.h:901 [inline]
 slab_free_hook mm/slub.c:2290 [inline]
 slab_free mm/slub.c:4598 [inline]
 kmem_cache_free+0x2ef/0x4c0 mm/slub.c:4700
 anon_vma_free mm/rmap.c:137 [inline]
 __put_anon_vma+0x114/0x3a0 mm/rmap.c:2568
 put_anon_vma include/linux/rmap.h:116 [inline]
 unlink_anon_vmas+0x58a/0x820 mm/rmap.c:444
 free_pgtables+0x33c/0x950 mm/memory.c:407
 exit_mmap+0x3d7/0xb20 mm/mmap.c:1679
 __mmput+0x12a/0x4c0 kernel/fork.c:1353
 mmput+0x62/0x70 kernel/fork.c:1375
 exit_mm kernel/exit.c:570 [inline]
 do_exit+0x9bf/0x2d70 kernel/exit.c:925
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0x661/0x1080 mm/page_alloc.c:2657
 kasan_depopulate_vmalloc_pte+0x63/0x80 mm/kasan/shadow.c:408
 apply_to_pte_range mm/memory.c:2831 [inline]
 apply_to_pmd_range mm/memory.c:2875 [inline]
 apply_to_pud_range mm/memory.c:2911 [inline]
 apply_to_p4d_range mm/memory.c:2947 [inline]
 __apply_to_page_range+0x5fd/0xd30 mm/memory.c:2981
 kasan_release_vmalloc+0xd1/0xe0 mm/kasan/shadow.c:529
 kasan_release_vmalloc_node mm/vmalloc.c:2196 [inline]
 purge_vmap_node+0x1d1/0xa40 mm/vmalloc.c:2213
 __purge_vmap_area_lazy+0x9bf/0xc10 mm/vmalloc.c:2304
 _vm_unmap_aliases+0x448/0x670 mm/vmalloc.c:2899
 change_page_attr_set_clr+0x240/0x480 arch/x86/mm/pat/set_memory.c:1881
 change_page_attr_set arch/x86/mm/pat/set_memory.c:1922 [inline]
 set_memory_nx+0xb6/0x110 arch/x86/mm/pat/set_memory.c:2110
 free_init_pages+0x79/0xd0 arch/x86/mm/init.c:929
 free_kernel_image_pages+0x24/0x50 arch/x86/mm/init.c:948
 kernel_init+0x30/0x2b0 init/main.c:1475
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff88802fd2eb00: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff88802fd2eb80: fa fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc
>ffff88802fd2ec00: 00 00 00 05 fc fc fc fc fa fb fb fb fc fc fc fc
                            ^
 ffff88802fd2ec80: fa fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc
 ffff88802fd2ed00: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
==================================================================