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BUG: KASAN: use-after-free in sysv_new_inode+0x10b4/0x1240 fs/sysv/ialloc.c:153
Read of size 2 at addr ffff88801edbb1ce by task syz.1.7/4274

CPU: 0 PID: 4274 Comm: syz.1.7 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 sysv_new_inode+0x10b4/0x1240 fs/sysv/ialloc.c:153
 sysv_mknod+0x4a/0xd0 fs/sysv/namei.c:53
 vfs_create+0x2db/0x460 fs/namei.c:3162
 do_mknodat+0x39d/0x620 fs/namei.c:3994
 __do_sys_mknod fs/namei.c:4027 [inline]
 __se_sys_mknod fs/namei.c:4025 [inline]
 __x64_sys_mknod+0x8a/0xa0 fs/namei.c:4025
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f329ad11969
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:00007f3298b79038 EFLAGS: 00000246 ORIG_RAX: 0000000000000085
RAX: ffffffffffffffda RBX: 00007f329af38fa0 RCX: 00007f329ad11969
RDX: 0000000000000702 RSI: 0000000000000400 RDI: 00002000000000c0
RBP: 00007f329ad93ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f329af38fa0 R15: 00007ffefd4a0c28
 </TASK>

The buggy address belongs to the page:
page:ffffea00007b6ec0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1edbb
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea000094ae48 ffffea0001d427c8 0000000000000000
raw: 0000000000000000 00000000000f0000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 4131, ts 47482838301, free_ts 65481599150
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5466
 alloc_slab_page mm/slub.c:1775 [inline]
 allocate_slab mm/slub.c:1912 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1975
 ___slab_alloc+0x81e/0xdf0 mm/slub.c:3008
 __slab_alloc mm/slub.c:3095 [inline]
 slab_alloc_node mm/slub.c:3186 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0x195/0x290 mm/slub.c:3233
 vm_area_dup+0x1e/0xb0 kernel/fork.c:358
 __split_vma+0xb1/0x410 mm/mmap.c:2718
 __do_munmap+0x375/0xdc0 mm/mmap.c:2844
 do_munmap mm/mmap.c:2898 [inline]
 munmap_vma_range mm/mmap.c:602 [inline]
 __mmap_region mm/mmap.c:1745 [inline]
 mmap_region+0x762/0x15e0 mm/mmap.c:2921
 do_mmap+0x77a/0xdf0 mm/mmap.c:1574
 vm_mmap_pgoff+0x1b2/0x2b0 mm/util.c:551
 ksys_mmap_pgoff+0x542/0x780 mm/mmap.c:1623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x94/0x280 mm/page_alloc.c:3396
 free_slab mm/slub.c:2015 [inline]
 discard_slab mm/slub.c:2021 [inline]
 __unfreeze_partials+0x1a5/0x200 mm/slub.c:2507
 put_cpu_partial+0x12d/0x190 mm/slub.c:2587
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3220 [inline]
 kmem_cache_alloc_node+0x12d/0x2d0 mm/slub.c:3256
 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1162 [inline]
 mld_newpack+0x12a/0xb90 net/ipv6/mcast.c:1746
 add_grhead+0x5a/0x240 net/ipv6/mcast.c:1857
 add_grec+0x1341/0x15d0 net/ipv6/mcast.c:1995
 mld_send_initial_cr+0xed/0x240 net/ipv6/mcast.c:2242
 ipv6_mc_dad_complete+0x84/0x210 net/ipv6/mcast.c:2253
 addrconf_dad_completed+0x6c7/0xca0 net/ipv6/addrconf.c:4258

Memory state around the buggy address:
 ffff88801edbb080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88801edbb100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88801edbb180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff88801edbb200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88801edbb280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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