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BUG: KASAN: use-after-free in sysv_new_inode+0x1105/0x1290 fs/sysv/ialloc.c:153
Read of size 2 at addr ffff88806c89e1ce by task syz-executor.0/4469

CPU: 1 PID: 4469 Comm: syz-executor.0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 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+0x1105/0x1290 fs/sysv/ialloc.c:153
 sysv_mknod+0x4a/0xd0 fs/sysv/namei.c:53
 lookup_open fs/namei.c:3470 [inline]
 open_last_lookups fs/namei.c:3540 [inline]
 path_openat+0x120a/0x2fb0 fs/namei.c:3747
 do_filp_open+0x1df/0x400 fs/namei.c:3777
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 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: 0033:0x7f5d3f2de279
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5d3e66e0b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f5d3f41bf80 RCX: 00007f5d3f2de279
RDX: 0000000000002c41 RSI: 0000000020000040 RDI: ffffffffffffff9c
RBP: 00007f5d3f33f49c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f5d3f41bf80 R15: 00007fffabfd8de8
 </TASK>

The buggy address belongs to the page:
page:ffffea0001b22780 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x6c89e
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea000179f508 ffffea0001697308 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 6568, ts 176403935148, free_ts 176405091665
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_pages_vma+0x2bc/0x790 mm/mempolicy.c:2146
 do_anonymous_page mm/memory.c:3838 [inline]
 handle_pte_fault mm/memory.c:4648 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x23be/0x4440 mm/memory.c:4883
 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
 handle_page_fault arch/x86/mm/fault.c:1443 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
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_list+0x119/0x830 mm/page_alloc.c:3433
 release_pages+0x185f/0x1bd0 mm/swap.c:963
 tlb_batch_pages_flush mm/mmu_gather.c:50 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:241 [inline]
 tlb_flush_mmu mm/mmu_gather.c:248 [inline]
 tlb_finish_mmu+0x1b4/0x370 mm/mmu_gather.c:371
 unmap_region+0x344/0x3b0 mm/mmap.c:2669
 __do_munmap+0xa29/0xe10 mm/mmap.c:2899
 __vm_munmap+0x13f/0x240 mm/mmap.c:2952
 __do_sys_munmap mm/mmap.c:2978 [inline]
 __se_sys_munmap mm/mmap.c:2974 [inline]
 __x64_sys_munmap+0x67/0x70 mm/mmap.c:2974
 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

Memory state around the buggy address:
 ffff88806c89e080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806c89e100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88806c89e180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff88806c89e200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806c89e280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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