loop2: detected capacity change from 0 to 128 VFS: Found a Xenix FS (block size = 1024) on device loop2 ================================================================== BUG: KASAN: slab-use-after-free in sysv_new_inode+0x10c5/0x1270 fs/sysv/ialloc.c:153 Read of size 2 at addr ffff8880750051ce by task syz.2.501/7007 CPU: 1 PID: 7007 Comm: syz.2.501 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0xac/0x220 mm/kasan/report.c:468 kasan_report+0x117/0x150 mm/kasan/report.c:581 sysv_new_inode+0x10c5/0x1270 fs/sysv/ialloc.c:153 sysv_symlink+0x9f/0x160 fs/sysv/namei.c:80 vfs_symlink+0x138/0x2b0 fs/namei.c:4481 do_symlinkat+0x1b2/0x3f0 fs/namei.c:4507 __do_sys_symlink fs/namei.c:4528 [inline] __se_sys_symlink fs/namei.c:4526 [inline] __x64_sys_symlink+0x7e/0x90 fs/namei.c:4526 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f0c5a38f749 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:00007f0c5b2cd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 00007f0c5a5e5fa0 RCX: 00007f0c5a38f749 RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000200000000200 RBP: 00007f0c5a413f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0c5a5e6038 R14: 00007f0c5a5e5fa0 R15: 00007ffcc6422908 Allocated by task 963: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767 slab_alloc_node mm/slub.c:3495 [inline] kmem_cache_alloc_node+0x150/0x330 mm/slub.c:3540 __alloc_skb+0x108/0x2c0 net/core/skbuff.c:643 alloc_skb include/linux/skbuff.h:1284 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline] nsim_dev_trap_report_work+0x293/0xb00 drivers/net/netdevsim/dev.c:851 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 Freed by task 963: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1811 [inline] slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1837 slab_free mm/slub.c:3830 [inline] kmem_cache_free+0xf8/0x280 mm/slub.c:3852 nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline] nsim_dev_trap_report_work+0x76f/0xb00 drivers/net/netdevsim/dev.c:851 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 The buggy address belongs to the object at ffff888075005140 which belongs to the cache skbuff_head_cache of size 240 The buggy address is located 142 bytes inside of freed 240-byte region [ffff888075005140, ffff888075005230) The buggy address belongs to the physical page: page:ffffea0001d40140 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x75005 flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000800 ffff88801e25c3c0 ffffea000070e3c0 dead000000000004 raw: 0000000000000000 00000000000c000c 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 5432, tgid 5432 (dhcpcd), ts 72442066993, free_ts 72438393337 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554 prep_new_page mm/page_alloc.c:1561 [inline] get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457 alloc_slab_page+0x5d/0x170 mm/slub.c:1881 allocate_slab mm/slub.c:2028 [inline] new_slab+0x87/0x2e0 mm/slub.c:2081 ___slab_alloc+0xc6d/0x1300 mm/slub.c:3253 __slab_alloc mm/slub.c:3339 [inline] __slab_alloc_node mm/slub.c:3392 [inline] slab_alloc_node mm/slub.c:3485 [inline] kmem_cache_alloc_node+0x1ea/0x330 mm/slub.c:3540 __alloc_skb+0x108/0x2c0 net/core/skbuff.c:643 alloc_skb include/linux/skbuff.h:1284 [inline] alloc_skb_with_frags+0xca/0x7c0 net/core/skbuff.c:6332 sock_alloc_send_pskb+0x857/0x990 net/core/sock.c:2821 unix_dgram_sendmsg+0x5a1/0x1720 net/unix/af_unix.c:2001 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] sock_write_iter+0x2bb/0x3f0 net/socket.c:1160 call_write_iter include/linux/fs.h:2018 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x43b/0x940 fs/read_write.c:584 ksys_write+0x147/0x250 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1154 [inline] free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429 mm_free_pgd kernel/fork.c:809 [inline] __mmdrop+0xb4/0x3d0 kernel/fork.c:925 mmdrop include/linux/sched/mm.h:54 [inline] mmdrop_sched include/linux/sched/mm.h:82 [inline] mmdrop_lazy_tlb_sched include/linux/sched/mm.h:109 [inline] finish_task_switch+0x3e0/0x920 kernel/sched/core.c:5280 context_switch kernel/sched/core.c:5384 [inline] __schedule+0x14da/0x44d0 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 do_wait+0x778/0xaf0 kernel/exit.c:1636 kernel_wait4+0x1af/0x270 kernel/exit.c:1780 __do_sys_wait4 kernel/exit.c:1808 [inline] __se_sys_wait4 kernel/exit.c:1804 [inline] __x64_sys_wait4+0x134/0x1e0 kernel/exit.c:1804 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Memory state around the buggy address: ffff888075005080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc ffff888075005100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff888075005180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888075005200: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc ffff888075005280: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================