================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946 Read of size 4 at addr ffff888126e18018 by task kworker/u4:16/8913 CPU: 1 PID: 8913 Comm: kworker/u4:16 Not tainted 5.15.189-syzkaller-00091-gf32b52534f1d #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: writeback wb_workfn (flush-7:0) Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report+0xf1/0x140 mm/kasan/report.c:444 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 ext4_ext_binsearch fs/ext4/extents.c:827 [inline] ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946 ext4_ext_map_blocks+0x1de/0x6280 fs/ext4/extents.c:4166 ext4_map_blocks+0x97b/0x1b20 fs/ext4/inode.c:674 mpage_map_one_extent fs/ext4/inode.c:2421 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2474 [inline] ext4_writepages+0x11e7/0x2f90 fs/ext4/inode.c:2842 do_writepages+0x48a/0x6c0 mm/page-writeback.c:2388 __writeback_single_inode+0xd5/0x9c0 fs/fs-writeback.c:1647 writeback_sb_inodes+0x9c0/0x1590 fs/fs-writeback.c:1930 wb_writeback+0x3f1/0x980 fs/fs-writeback.c:2106 wb_do_writeback fs/fs-writeback.c:2253 [inline] wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2294 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472 kthread+0x411/0x500 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Allocated by task 12685: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:433 [inline] ____kasan_kmalloc mm/kasan/common.c:512 [inline] __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:521 kasan_kmalloc include/linux/kasan.h:227 [inline] kmem_cache_alloc_trace+0x119/0x270 mm/slub.c:3269 kmalloc include/linux/slab.h:616 [inline] kzalloc include/linux/slab.h:747 [inline] kobject_uevent_env+0x272/0x700 lib/kobject_uevent.c:539 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 rx_queue_add_kobject net/core/net-sysfs.c:1070 [inline] net_rx_queue_update_kobjects+0x21d/0x480 net/core/net-sysfs.c:1110 register_queue_kobjects net/core/net-sysfs.c:1767 [inline] netdev_register_kobject+0x229/0x320 net/core/net-sysfs.c:2018 register_netdevice+0xdfa/0x13a0 net/core/dev.c:10405 __ip_tunnel_create+0x2bf/0x380 net/ipv4/ip_tunnel.c:267 ip_tunnel_init_net+0x290/0x740 net/ipv4/ip_tunnel.c:1084 erspan_init_net+0x29/0x30 net/ipv4/ip_gre.c:1723 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:138 setup_net+0x344/0xa90 net/core/net_namespace.c:332 copy_net_ns+0x355/0x5c0 net/core/net_namespace.c:476 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110 copy_namespaces+0x1d1/0x220 kernel/nsproxy.c:178 copy_process+0x118d/0x3210 kernel/fork.c:2351 kernel_clone+0x23f/0x940 kernel/fork.c:2737 __do_sys_clone kernel/fork.c:2863 [inline] __se_sys_clone kernel/fork.c:2847 [inline] __x64_sys_clone+0x176/0x1d0 kernel/fork.c:2847 x64_sys_call+0x41f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:57 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 Freed by task 12685: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1749 slab_free mm/slub.c:3521 [inline] kfree+0xc4/0x270 mm/slub.c:4583 kobject_uevent_env+0x34d/0x700 lib/kobject_uevent.c:641 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 rx_queue_add_kobject net/core/net-sysfs.c:1070 [inline] net_rx_queue_update_kobjects+0x21d/0x480 net/core/net-sysfs.c:1110 register_queue_kobjects net/core/net-sysfs.c:1767 [inline] netdev_register_kobject+0x229/0x320 net/core/net-sysfs.c:2018 register_netdevice+0xdfa/0x13a0 net/core/dev.c:10405 __ip_tunnel_create+0x2bf/0x380 net/ipv4/ip_tunnel.c:267 ip_tunnel_init_net+0x290/0x740 net/ipv4/ip_tunnel.c:1084 erspan_init_net+0x29/0x30 net/ipv4/ip_gre.c:1723 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:138 setup_net+0x344/0xa90 net/core/net_namespace.c:332 copy_net_ns+0x355/0x5c0 net/core/net_namespace.c:476 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110 copy_namespaces+0x1d1/0x220 kernel/nsproxy.c:178 copy_process+0x118d/0x3210 kernel/fork.c:2351 kernel_clone+0x23f/0x940 kernel/fork.c:2737 __do_sys_clone kernel/fork.c:2863 [inline] __se_sys_clone kernel/fork.c:2847 [inline] __x64_sys_clone+0x176/0x1d0 kernel/fork.c:2847 x64_sys_call+0x41f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:57 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 The buggy address belongs to the object at ffff888126e18000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 24 bytes inside of 4096-byte region [ffff888126e18000, ffff888126e19000) The buggy address belongs to the page: page:ffffea00049b8600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x126e18 head:ffffea00049b8600 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100043380 raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 284, ts 27068261201, free_ts 0 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611 get_page_from_freelist+0x2cc5/0x2d50 mm/page_alloc.c:4485 __alloc_pages+0x18f/0x440 mm/page_alloc.c:5795 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1932 [inline] new_slab+0xa1/0x4d0 mm/slub.c:1995 ___slab_alloc+0x381/0x810 mm/slub.c:3028 __slab_alloc+0x49/0x90 mm/slub.c:3115 slab_alloc_node mm/slub.c:3206 [inline] slab_alloc mm/slub.c:3250 [inline] __kmalloc_track_caller+0x169/0x2c0 mm/slub.c:4949 kmemdup+0x26/0x60 mm/util.c:132 __addrconf_sysctl_register+0xad/0x3d0 net/ipv6/addrconf.c:7132 addrconf_sysctl_register+0x147/0x1a0 net/ipv6/addrconf.c:7197 ipv6_add_dev+0xc03/0x1150 net/ipv6/addrconf.c:454 addrconf_notify+0x582/0xde0 net/ipv6/addrconf.c:3597 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:391 call_netdevice_notifiers_info net/core/dev.c:2057 [inline] call_netdevice_notifiers_extack net/core/dev.c:2069 [inline] call_netdevice_notifiers+0x111/0x190 net/core/dev.c:2083 register_netdevice+0x1039/0x13a0 net/core/dev.c:10436 page_owner free stack trace missing Memory state around the buggy address: ffff888126e17f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888126e17f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888126e18000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888126e18080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888126e18100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== EXT4-fs error (device loop0): ext4_map_blocks:740: inode #15: block 255885561561088: comm kworker/u4:16: lblock 0 mapped to illegal pblock 255885561561088 (length 1) EXT4-fs (loop0): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 117 EXT4-fs (loop0): This should not happen!! Data will be lost