================================================================== 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 ffff88811272a018 by task kworker/u4:4/320 CPU: 0 PID: 320 Comm: kworker/u4:4 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: writeback wb_workfn (flush-7:2) 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+0x1db/0x6270 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:1657 writeback_sb_inodes+0x9c0/0x1590 fs/fs-writeback.c:1940 wb_writeback+0x3f1/0x980 fs/fs-writeback.c:2116 wb_do_writeback fs/fs-writeback.c:2263 [inline] wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2304 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 426: 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:3274 kmalloc include/linux/slab.h:619 [inline] kzalloc include/linux/slab.h:750 [inline] kobject_uevent_env+0x272/0x700 lib/kobject_uevent.c:539 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 netdev_queue_add_kobject net/core/net-sysfs.c:1677 [inline] netdev_queue_update_kobjects+0x1c9/0x3e0 net/core/net-sysfs.c:1711 register_queue_kobjects net/core/net-sysfs.c:1772 [inline] netdev_register_kobject+0x26e/0x320 net/core/net-sysfs.c:2018 register_netdevice+0xdfa/0x13a0 net/core/dev.c:10405 veth_newlink+0x668/0xda0 drivers/net/veth.c:1683 __rtnl_newlink net/core/rtnetlink.c:3524 [inline] rtnl_newlink+0x112d/0x17b0 net/core/rtnetlink.c:3572 rtnetlink_rcv_msg+0x9e4/0xb90 net/core/rtnetlink.c:5650 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2511 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5668 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x86a/0xb70 net/netlink/af_netlink.c:1922 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] __sys_sendto+0x423/0x580 net/socket.c:2063 __do_sys_sendto net/socket.c:2075 [inline] __se_sys_sendto net/socket.c:2071 [inline] __x64_sys_sendto+0xe5/0x100 net/socket.c:2071 x64_sys_call+0x178/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:45 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 426: 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:1728 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754 slab_free mm/slub.c:3526 [inline] kfree+0xc4/0x270 mm/slub.c:4588 kobject_uevent_env+0x34d/0x700 lib/kobject_uevent.c:641 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 netdev_queue_add_kobject net/core/net-sysfs.c:1677 [inline] netdev_queue_update_kobjects+0x1c9/0x3e0 net/core/net-sysfs.c:1711 register_queue_kobjects net/core/net-sysfs.c:1772 [inline] netdev_register_kobject+0x26e/0x320 net/core/net-sysfs.c:2018 register_netdevice+0xdfa/0x13a0 net/core/dev.c:10405 veth_newlink+0x668/0xda0 drivers/net/veth.c:1683 __rtnl_newlink net/core/rtnetlink.c:3524 [inline] rtnl_newlink+0x112d/0x17b0 net/core/rtnetlink.c:3572 rtnetlink_rcv_msg+0x9e4/0xb90 net/core/rtnetlink.c:5650 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2511 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5668 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x86a/0xb70 net/netlink/af_netlink.c:1922 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] __sys_sendto+0x423/0x580 net/socket.c:2063 __do_sys_sendto net/socket.c:2075 [inline] __se_sys_sendto net/socket.c:2071 [inline] __x64_sys_sendto+0xe5/0x100 net/socket.c:2071 x64_sys_call+0x178/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:45 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 ffff88811272a000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 24 bytes inside of 4096-byte region [ffff88811272a000, ffff88811272b000) The buggy address belongs to the page: page:ffffea000449ca00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112728 head:ffffea000449ca00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 426, ts 45122719769, free_ts 27310655106 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:5808 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1937 [inline] new_slab+0xa1/0x4d0 mm/slub.c:2000 ___slab_alloc+0x381/0x810 mm/slub.c:3033 __slab_alloc+0x49/0x90 mm/slub.c:3120 slab_alloc_node mm/slub.c:3211 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc_trace+0x146/0x270 mm/slub.c:3272 kmalloc include/linux/slab.h:619 [inline] kzalloc include/linux/slab.h:750 [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 veth_newlink+0x668/0xda0 drivers/net/veth.c:1683 __rtnl_newlink net/core/rtnetlink.c:3524 [inline] rtnl_newlink+0x112d/0x17b0 net/core/rtnetlink.c:3572 rtnetlink_rcv_msg+0x9e4/0xb90 net/core/rtnetlink.c:5650 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1472 [inline] free_pcp_prepare mm/page_alloc.c:1544 [inline] free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534 free_unref_page+0xa2/0x550 mm/page_alloc.c:3616 free_the_page mm/page_alloc.c:805 [inline] __free_pages+0x6c/0x100 mm/page_alloc.c:5884 __free_slab+0xe8/0x1e0 mm/slub.c:2025 free_slab mm/slub.c:2040 [inline] discard_slab mm/slub.c:2046 [inline] __unfreeze_partials+0x160/0x190 mm/slub.c:2532 put_cpu_partial+0xc6/0x120 mm/slub.c:2612 __slab_free+0x1d4/0x290 mm/slub.c:3395 do_slab_free mm/slub.c:3514 [inline] ___cache_free+0x104/0x120 mm/slub.c:3535 qlink_free+0x4d/0x90 mm/kasan/quarantine.c:157 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:443 kasan_slab_alloc include/linux/kasan.h:217 [inline] slab_post_alloc_hook+0x4f/0x2b0 mm/slab.h:550 slab_alloc_node mm/slub.c:3245 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc+0xf7/0x260 mm/slub.c:3260 kmem_cache_alloc_node include/linux/slab.h:492 [inline] __alloc_skb+0xe0/0x740 net/core/skbuff.c:416 alloc_skb include/linux/skbuff.h:1183 [inline] nlmsg_new include/net/netlink.h:953 [inline] rtmsg_ifa+0xfa/0x1d0 net/ipv4/devinet.c:1927 Memory state around the buggy address: ffff888112729f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888112729f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88811272a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88811272a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811272a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 84 with max blocks 2 with error 117 EXT4-fs (loop2): This should not happen!! Data will be lost EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 84 with max blocks 2 with error 117 EXT4-fs (loop2): This should not happen!! Data will be lost EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 84 with max blocks 2 with error 117 EXT4-fs (loop2): This should not happen!! Data will be lost EXT4-fs error (device loop2): ext4_ext_split:1074: inode #15: comm kworker/u4:4: p_ext > EXT_MAX_EXTENT! EXT4-fs error (device loop2): mb_free_blocks:1860: group 0, inode 15: block 449:freeing already freed block (bit 28); block bitmap corrupt. EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 84 with max blocks 2 with error 117 EXT4-fs (loop2): This should not happen!! Data will be lost EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 84 with max blocks 2 with error 117 EXT4-fs (loop2): This should not happen!! Data will be lost