================================================================== BUG: KASAN: slab-use-after-free in memcmp lib/string.c:676 [inline] BUG: KASAN: slab-use-after-free in bcmp+0xc0/0x1e0 lib/string.c:708 Read of size 8 at addr ffff8880595b2028 by task syz.0.1437/15684 CPU: 0 UID: 0 PID: 15684 Comm: syz.0.1437 Not tainted 6.14.0-rc7-syzkaller-00205-g586de92313fc #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0x16e/0x5b0 mm/kasan/report.c:521 kasan_report+0x143/0x180 mm/kasan/report.c:634 memcmp lib/string.c:676 [inline] bcmp+0xc0/0x1e0 lib/string.c:708 _Z6memcmpPKvU25pass_dynamic_object_size0S0_U25pass_dynamic_object_size0m include/linux/fortify-string.h:727 [inline] __bch2_uuid_to_fs fs/bcachefs/super.c:221 [inline] bch2_fs_online+0x20b/0x860 fs/bcachefs/super.c:701 bch2_fs_alloc fs/bcachefs/super.c:955 [inline] bch2_fs_open+0x3175/0x31e0 fs/bcachefs/super.c:2065 bch2_fs_get_tree+0x738/0x17a0 fs/bcachefs/fs.c:2190 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 do_new_mount+0x2be/0xb40 fs/namespace.c:3560 do_mount fs/namespace.c:3900 [inline] __do_sys_mount fs/namespace.c:4111 [inline] __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4088 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f12e698e90a Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f12e78cde68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f12e78cdef0 RCX: 00007f12e698e90a RDX: 0000200000000000 RSI: 0000200000000040 RDI: 00007f12e78cdeb0 RBP: 0000200000000000 R08: 00007f12e78cdef0 R09: 0000000000808040 R10: 0000000000808040 R11: 0000000000000246 R12: 0000200000000040 R13: 00007f12e78cdeb0 R14: 0000000000005943 R15: 0000200000000300 Allocated by task 15671: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4294 [inline] __kmalloc_node_track_caller_noprof+0x28b/0x4c0 mm/slub.c:4313 __do_krealloc mm/slub.c:4820 [inline] krealloc_noprof+0x10f/0x300 mm/slub.c:4873 bch2_sb_realloc+0x2d2/0x660 fs/bcachefs/super-io.c:206 __copy_super+0x546/0x920 fs/bcachefs/super-io.c:637 bch2_sb_to_fs+0xab/0x150 fs/bcachefs/super-io.c:664 bch2_fs_alloc fs/bcachefs/super.c:834 [inline] bch2_fs_open+0x160f/0x31e0 fs/bcachefs/super.c:2065 bch2_fs_get_tree+0x738/0x17a0 fs/bcachefs/fs.c:2190 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 do_new_mount+0x2be/0xb40 fs/namespace.c:3560 do_mount fs/namespace.c:3900 [inline] __do_sys_mount fs/namespace.c:4111 [inline] __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4088 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 15671: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2353 [inline] slab_free mm/slub.c:4609 [inline] kfree+0x196/0x430 mm/slub.c:4757 krealloc_noprof+0x1ad/0x300 bch2_sb_realloc+0x2d2/0x660 fs/bcachefs/super-io.c:206 bch2_sb_field_resize_id+0x14d/0x4a0 fs/bcachefs/super-io.c:238 bch2_sb_counters_from_cpu+0xac/0x300 fs/bcachefs/sb-counters.c:67 bch2_write_super+0xe1e/0x3cd0 fs/bcachefs/super-io.c:1029 bch2_fs_initialize+0x2a5/0x1610 fs/bcachefs/recovery.c:1102 bch2_fs_start+0x36d/0x610 fs/bcachefs/super.c:1042 bch2_fs_get_tree+0xdb7/0x17a0 fs/bcachefs/fs.c:2203 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 do_new_mount+0x2be/0xb40 fs/namespace.c:3560 do_mount fs/namespace.c:3900 [inline] __do_sys_mount fs/namespace.c:4111 [inline] __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4088 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff8880595b2000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 40 bytes inside of freed 4096-byte region [ffff8880595b2000, ffff8880595b3000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x595b0 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b042140 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b042140 0000000000000000 dead000000000001 head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0001656c01 ffffffffffffffff 0000000000000000 head: 0000000000000008 0000000000000000 00000000ffffffff 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1148, tgid 1148 (kworker/u8:6), ts 107344601653, free_ts 107330798685 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1551 prep_new_page mm/page_alloc.c:1559 [inline] get_page_from_freelist+0x3651/0x37a0 mm/page_alloc.c:3477 __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4740 alloc_pages_mpol+0x311/0x660 mm/mempolicy.c:2270 alloc_slab_page mm/slub.c:2423 [inline] allocate_slab+0x8f/0x3a0 mm/slub.c:2587 new_slab mm/slub.c:2640 [inline] ___slab_alloc+0xc27/0x14a0 mm/slub.c:3826 __slab_alloc+0x58/0xa0 mm/slub.c:3916 __slab_alloc_node mm/slub.c:3991 [inline] slab_alloc_node mm/slub.c:4152 [inline] __do_kmalloc_node mm/slub.c:4293 [inline] __kmalloc_node_track_caller_noprof+0x2e9/0x4c0 mm/slub.c:4313 kmalloc_reserve+0x111/0x2a0 net/core/skbuff.c:537 __alloc_skb+0x1f3/0x440 net/core/skbuff.c:606 alloc_skb include/linux/skbuff.h:1331 [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+0x261/0xb50 drivers/net/netdevsim/dev.c:851 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xabe/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd30 kernel/workqueue.c:3400 kthread+0x7a9/0x920 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 page last free pid 47 tgid 47 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1127 [inline] free_frozen_pages+0xe04/0x10e0 mm/page_alloc.c:2660 discard_slab mm/slub.c:2684 [inline] __put_partials+0x160/0x1c0 mm/slub.c:3153 put_cpu_partial+0x17c/0x250 mm/slub.c:3228 __slab_free+0x290/0x380 mm/slub.c:4479 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4115 [inline] slab_alloc_node mm/slub.c:4164 [inline] __do_kmalloc_node mm/slub.c:4293 [inline] __kmalloc_node_noprof+0x23c/0x4d0 mm/slub.c:4300 __kvmalloc_node_noprof+0x72/0x190 mm/util.c:665 bucket_table_alloc lib/rhashtable.c:186 [inline] rhashtable_rehash_alloc+0x9e/0x290 lib/rhashtable.c:367 rhashtable_shrink lib/rhashtable.c:411 [inline] rht_deferred_worker+0x2075/0x23f0 lib/rhashtable.c:429 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xabe/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd30 kernel/workqueue.c:3400 kthread+0x7a9/0x920 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Memory state around the buggy address: ffff8880595b1f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880595b1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880595b2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880595b2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880595b2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================