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BUG: KASAN: slab-out-of-bounds in dns_resolver_preparse+0xcaf/0xd20 net/dns_resolver/dns_key.c:127
Read of size 1 at addr ffff8880788c9a54 by task syz-executor.2/22649

CPU: 1 PID: 22649 Comm: syz-executor.2 Not tainted 6.1.71-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:284 [inline]
 print_report+0x15f/0x4f0 mm/kasan/report.c:395
 kasan_report+0x136/0x160 mm/kasan/report.c:495
 dns_resolver_preparse+0xcaf/0xd20 net/dns_resolver/dns_key.c:127
 key_create_or_update+0x47b/0xbf0 security/keys/key.c:861
 __do_sys_add_key security/keys/keyctl.c:134 [inline]
 __se_sys_add_key+0x33b/0x480 security/keys/keyctl.c:74
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc5a5c7cd29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc5a6a300c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000f8
RAX: ffffffffffffffda RBX: 00007fc5a5dabf80 RCX: 00007fc5a5c7cd29
RDX: 0000000020000080 RSI: 0000000000000000 RDI: 00000000200003c0
RBP: 00007fc5a5cc947a R08: 000000003fecc02a R09: 0000000000000000
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fc5a5dabf80 R15: 00007ffd22cdaeb8
 </TASK>

Allocated by task 22649:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:955 [inline]
 __kmalloc_node+0xb3/0x230 mm/slab_common.c:962
 kmalloc_node include/linux/slab.h:579 [inline]
 kvmalloc_node+0x6e/0x180 mm/util.c:581
 kvmalloc include/linux/slab.h:706 [inline]
 __do_sys_add_key security/keys/keyctl.c:116 [inline]
 __se_sys_add_key+0x26c/0x480 security/keys/keyctl.c:74
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff8880788c9a50
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 4 bytes inside of
 8-byte region [ffff8880788c9a50, ffff8880788c9a58)

The buggy address belongs to the physical page:
page:ffffea0001e23240 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880788c9c30 pfn:0x788c9
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000001 ffff888012441280
raw: ffff8880788c9c30 0000000080660050 00000001ffffffff 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 5392, tgid 5367 (syz-executor.0), ts 360336029217, free_ts 359249733236
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2513
 prep_new_page mm/page_alloc.c:2520 [inline]
 get_page_from_freelist+0x31a1/0x3320 mm/page_alloc.c:4279
 __alloc_pages+0x28d/0x770 mm/page_alloc.c:5545
 alloc_slab_page+0x6a/0x150 mm/slub.c:1794
 allocate_slab mm/slub.c:1939 [inline]
 new_slab+0x84/0x2d0 mm/slub.c:1992
 ___slab_alloc+0xc20/0x1270 mm/slub.c:3180
 __slab_alloc mm/slub.c:3279 [inline]
 slab_alloc_node mm/slub.c:3364 [inline]
 __kmem_cache_alloc_node+0x19f/0x260 mm/slub.c:3437
 __do_kmalloc_node mm/slab_common.c:954 [inline]
 __kmalloc_node_track_caller+0xa0/0x220 mm/slab_common.c:975
 kstrdup mm/util.c:61 [inline]
 kstrdup_const+0x56/0x90 mm/util.c:84
 __kernfs_new_node+0x99/0x870 fs/kernfs/dir.c:604
 kernfs_new_node+0x95/0x160 fs/kernfs/dir.c:672
 kernfs_create_link+0xa1/0x1f0 fs/kernfs/symlink.c:39
 sysfs_do_create_link_sd+0x85/0x100 fs/sysfs/symlink.c:44
 device_add_class_symlinks drivers/base/core.c:3406 [inline]
 device_add+0x7d4/0xfd0 drivers/base/core.c:3612
 netdev_register_kobject+0x176/0x310 net/core/net-sysfs.c:2015
 register_netdevice+0x108a/0x1720 net/core/dev.c:10096
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1440 [inline]
 free_pcp_prepare mm/page_alloc.c:1490 [inline]
 free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3358
 free_unref_page_list+0x663/0x900 mm/page_alloc.c:3499
 release_pages+0x2836/0x2b40 mm/swap.c:1055
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu+0xfc/0x210 mm/mmu_gather.c:261
 tlb_finish_mmu+0xce/0x1f0 mm/mmu_gather.c:361
 exit_mmap+0x3c3/0x9f0 mm/mmap.c:3239
 __mmput+0x115/0x3c0 kernel/fork.c:1199
 exit_mm+0x226/0x300 kernel/exit.c:563
 do_exit+0x9f6/0x26a0 kernel/exit.c:856
 __do_sys_exit kernel/exit.c:986 [inline]
 __se_sys_exit kernel/exit.c:984 [inline]
 __x64_sys_exit+0x3c/0x40 kernel/exit.c:984
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff8880788c9900: fc fc fa fc fc fc fc 00 fc fc fc fc 02 fc fc fc
 ffff8880788c9980: fc fa fc fc fc fc fb fc fc fc fc 00 fc fc fc fc
>ffff8880788c9a00: fb fc fc fc fc fa fc fc fc fc 04 fc fc fc fc fa
                                                 ^
 ffff8880788c9a80: fc fc fc fc fb fc fc fc fc fa fc fc fc fc fa fc
 ffff8880788c9b00: fc fc fc fa fc fc fc fc fa fc fc fc fc 05 fc fc
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