================================================================== BUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x41b6/0x4af0 fs/ext4/extents.c:2084 Read of size 4 at addr ffff888011279c18 by task syz.3.62/6323 CPU: 0 UID: 0 PID: 6323 Comm: syz.3.62 Not tainted 6.15.0-rc7-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xb4/0x290 mm/kasan/report.c:521 kasan_report+0x118/0x150 mm/kasan/report.c:634 ext4_ext_insert_extent+0x41b6/0x4af0 fs/ext4/extents.c:2084 ext4_ext_map_blocks+0x179c/0x67c0 fs/ext4/extents.c:4400 ext4_map_create_blocks fs/ext4/inode.c:520 [inline] ext4_map_blocks+0x807/0x1740 fs/ext4/inode.c:706 _ext4_get_block+0x200/0x4c0 fs/ext4/inode.c:785 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:818 ext4_block_write_begin+0x546/0x1290 fs/ext4/inode.c:1067 ext4_write_begin+0x6f6/0x12c0 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x33a/0xa60 fs/ext4/inode.c:2932 generic_perform_write+0x2c4/0x910 mm/filemap.c:4103 ext4_buffered_write_iter+0xce/0x3a0 fs/ext4/file.c:299 ext4_file_write_iter+0x298/0x1bc0 fs/ext4/file.c:-1 new_sync_write fs/read_write.c:591 [inline] vfs_write+0x54b/0xa90 fs/read_write.c:684 ksys_pwrite64 fs/read_write.c:791 [inline] __do_sys_pwrite64 fs/read_write.c:799 [inline] __se_sys_pwrite64 fs/read_write.c:796 [inline] __x64_sys_pwrite64+0x193/0x220 fs/read_write.c:796 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6110f8e969 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:00007f6111e88038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 RAX: ffffffffffffffda RBX: 00007f61111b5fa0 RCX: 00007f6110f8e969 RDX: 000000000000fdef RSI: 0000200000000140 RDI: 0000000000000005 RBP: 00007f6111010ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000fecc R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f61111b5fa0 R15: 00007ffdf1572838 Allocated by task 36: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:319 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:345 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4147 [inline] slab_alloc_node mm/slub.c:4196 [inline] kmem_cache_alloc_node_noprof+0x1bb/0x3c0 mm/slub.c:4248 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:658 alloc_skb include/linux/skbuff.h:1340 [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+0x29a/0xb80 drivers/net/netdevsim/dev.c:851 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xade/0x17a0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 36: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2380 [inline] slab_free mm/slub.c:4642 [inline] kmem_cache_free+0x192/0x3f0 mm/slub.c:4744 nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline] nsim_dev_trap_report_work+0x7cf/0xb80 drivers/net/netdevsim/dev.c:851 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xade/0x17a0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff888011279b40 which belongs to the cache skbuff_head_cache of size 240 The buggy address is located 216 bytes inside of freed 240-byte region [ffff888011279b40, ffff888011279c30) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11279 ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff8881412ec8c0 ffffea0000aa4ac0 dead000000000003 raw: 0000000000000000 00000000000c000c 00000000f5000000 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5828, tgid 5828 (syz-executor), ts 92495845799, free_ts 92226317535 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1d8/0x230 mm/page_alloc.c:1714 prep_new_page mm/page_alloc.c:1722 [inline] get_page_from_freelist+0x21c7/0x22a0 mm/page_alloc.c:3684 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4966 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2301 alloc_slab_page mm/slub.c:2450 [inline] allocate_slab+0x8a/0x3b0 mm/slub.c:2618 new_slab mm/slub.c:2672 [inline] ___slab_alloc+0xbfc/0x1480 mm/slub.c:3858 __slab_alloc mm/slub.c:3948 [inline] __slab_alloc_node mm/slub.c:4023 [inline] slab_alloc_node mm/slub.c:4184 [inline] kmem_cache_alloc_node_noprof+0x280/0x3c0 mm/slub.c:4248 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:658 alloc_skb include/linux/skbuff.h:1340 [inline] nlmsg_new include/net/netlink.h:1019 [inline] inet6_rt_notify+0xb6/0x240 net/ipv6/route.c:6258 fib6_add_rt2node net/ipv6/ip6_fib.c:1259 [inline] fib6_add+0x1d0d/0x4360 net/ipv6/ip6_fib.c:1488 __ip6_ins_rt net/ipv6/route.c:1351 [inline] ip6_route_add+0x8a/0x160 net/ipv6/route.c:3900 addrconf_add_mroute net/ipv6/addrconf.c:2551 [inline] addrconf_add_dev+0x24f/0x340 net/ipv6/addrconf.c:2569 addrconf_dev_config net/ipv6/addrconf.c:3477 [inline] addrconf_init_auto_addrs+0x5cf/0xb50 net/ipv6/addrconf.c:3571 addrconf_notify+0xacc/0x1010 net/ipv6/addrconf.c:3744 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline] call_netdevice_notifiers net/core/dev.c:2228 [inline] __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1 page last free pid 5827 tgid 5827 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1258 [inline] __free_frozen_pages+0xb05/0xcd0 mm/page_alloc.c:2721 __slab_free+0x326/0x400 mm/slub.c:4553 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4147 [inline] slab_alloc_node mm/slub.c:4196 [inline] __kmalloc_cache_noprof+0x1be/0x3d0 mm/slub.c:4353 kmalloc_noprof include/linux/slab.h:905 [inline] __netdev_adjacent_dev_insert+0x158/0x8d0 net/core/dev.c:8306 __netdev_adjacent_dev_link_lists net/core/dev.c:8398 [inline] __netdev_adjacent_dev_link_neighbour net/core/dev.c:8427 [inline] __netdev_upper_dev_link+0x341/0x590 net/core/dev.c:8487 netdev_upper_dev_link+0x9d/0xf0 net/core/dev.c:8533 macvlan_common_newlink+0x124a/0x1980 drivers/net/macvlan.c:1545 rtnl_newlink_create+0x308/0xaf0 net/core/rtnetlink.c:3833 __rtnl_newlink net/core/rtnetlink.c:3950 [inline] rtnl_newlink+0x16d6/0x1c70 net/core/rtnetlink.c:4065 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6955 netlink_rcv_skb+0x21c/0x490 net/netlink/af_netlink.c:2534 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883 Memory state around the buggy address: ffff888011279b00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff888011279b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888011279c00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc ^ ffff888011279c80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888011279d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc ==================================================================