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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+0x123b/0x14e0 fs/afs/addr_prefs.c:415
Read of size 1 at addr ffff888026ff4627 by task syz.6.6651/30944

CPU: 0 UID: 0 PID: 30944 Comm: syz.6.6651 Not tainted 6.13.0-rc3-syzkaller-00017-gf44d154d6e3d #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: 0033:0x7f2220185d19
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:00007f2220fec038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2220375fa0 RCX: 00007f2220185d19
RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f2220201a20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f2220375fa0 R15: 00007ffc54984478
 </TASK>

Allocated by task 30944:
 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:4298 [inline]
 __kmalloc_node_track_caller_noprof+0x21d/0x520 mm/slub.c:4317
 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 ffff888026ff4620
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of
 allocated 7-byte region [ffff888026ff4620, ffff888026ff4627)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x26ff4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801ac41500 ffffea0001b7ed00 dead000000000002
raw: 0000000000000000 0000000080800080 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 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5832, tgid 5832 (syz-executor), ts 93665389694, free_ts 93665227795
 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:2423 [inline]
 allocate_slab mm/slub.c:2589 [inline]
 new_slab+0x2c9/0x410 mm/slub.c:2642
 ___slab_alloc+0xce2/0x1650 mm/slub.c:3830
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3920
 __slab_alloc_node mm/slub.c:3995 [inline]
 slab_alloc_node mm/slub.c:4156 [inline]
 __do_kmalloc_node mm/slub.c:4297 [inline]
 __kmalloc_node_noprof+0x2f0/0x520 mm/slub.c:4304
 kmalloc_node_noprof include/linux/slab.h:928 [inline]
 __vmalloc_area_node mm/vmalloc.c:3645 [inline]
 __vmalloc_node_range_noprof+0x3d8/0x1530 mm/vmalloc.c:3844
 __vmalloc_node_noprof mm/vmalloc.c:3909 [inline]
 vzalloc_noprof+0x6b/0x90 mm/vmalloc.c:3982
 xt_counters_alloc+0x4c/0x70 net/netfilter/x_tables.c:1380
 __do_replace+0x99/0x9e0 net/ipv4/netfilter/arp_tables.c:894
 do_replace net/ipv6/netfilter/ip6_tables.c:1158 [inline]
 do_ip6t_set_ctl+0x990/0xc20 net/ipv6/netfilter/ip6_tables.c:1644
 nf_setsockopt+0x8a/0xf0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x135/0x170 net/ipv6/ipv6_sockglue.c:998
 tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:4030
page last free pid 5832 tgid 5832 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
 vfree+0x17a/0x890 mm/vmalloc.c:3382
 copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:882 [inline]
 get_entries net/ipv6/netfilter/ip6_tables.c:1039 [inline]
 do_ip6t_get_ctl+0x8ec/0xaf0 net/ipv6/netfilter/ip6_tables.c:1677
 nf_getsockopt+0x79/0xe0 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x1f7/0x280 net/ipv6/ipv6_sockglue.c:1493
 tcp_getsockopt+0x9e/0x100 net/ipv4/tcp.c:4671
 do_sock_getsockopt+0x3fe/0x870 net/socket.c:2374
 __sys_getsockopt+0x12f/0x260 net/socket.c:2403
 __do_sys_getsockopt net/socket.c:2410 [inline]
 __se_sys_getsockopt net/socket.c:2407 [inline]
 __x64_sys_getsockopt+0xbd/0x160 net/socket.c:2407
 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

Memory state around the buggy address:
 ffff888026ff4500: 05 fc fc fc 05 fc fc fc 05 fc fc fc 06 fc fc fc
 ffff888026ff4580: 00 fc fc fc 06 fc fc fc 05 fc fc fc 05 fc fc fc
>ffff888026ff4600: 05 fc fc fc 07 fc fc fc 05 fc fc fc 05 fc fc fc
                               ^
 ffff888026ff4680: 05 fc fc fc 05 fc fc fc 06 fc fc fc 05 fc fc fc
 ffff888026ff4700: 06 fc fc fc 06 fc fc fc 05 fc fc fc 05 fc fc fc
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