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List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:216e:b0:3dd:e7d7:3e1b with SMTP id e9e14a558f8ab-3de38cca784mr20093395ab.18.1750414802708; Fri, 20 Jun 2025 03:20:02 -0700 (PDT) Date: Fri, 20 Jun 2025 03:20:02 -0700 In-Reply-To: <20250620094529.1318-1-hdanton@sina.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <685535d2.a00a0220.137b3.0045.GAE@google.com> Subject: Re: [syzbot] [mm?] KASAN: slab-use-after-free Read in do_sync_mmap_readahead From: syzbot To: hdanton@sina.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: KASAN: slab-use-after-free Read in do_sync_mmap_readahead ================================================================== BUG: KASAN: slab-use-after-free in do_sync_mmap_readahead+0x4bf/0x830 mm/filemap.c:3282 Read of size 8 at addr ffff888028ba3410 by task syz.3.92/7189 CPU: 1 UID: 0 PID: 7189 Comm: syz.3.92 Not tainted 6.16.0-rc2-next-20250619-syzkaller-03877-g2c923c845768-dirty #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+0xd2/0x2b0 mm/kasan/report.c:521 kasan_report+0x118/0x150 mm/kasan/report.c:634 do_sync_mmap_readahead+0x4bf/0x830 mm/filemap.c:3282 filemap_fault+0x62c/0x1200 mm/filemap.c:3444 __do_fault+0x138/0x390 mm/memory.c:5187 do_read_fault mm/memory.c:5608 [inline] do_fault mm/memory.c:5742 [inline] do_pte_missing mm/memory.c:4269 [inline] handle_pte_fault mm/memory.c:6087 [inline] __handle_mm_fault+0x37ed/0x5620 mm/memory.c:6230 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6399 faultin_page mm/gup.c:1186 [inline] __get_user_pages+0x1b0c/0x3210 mm/gup.c:1491 populate_vma_page_range+0x29f/0x3a0 mm/gup.c:1931 __mm_populate+0x24c/0x380 mm/gup.c:2034 mm_populate include/linux/mm.h:3372 [inline] vm_mmap_pgoff+0x3f0/0x4c0 mm/util.c:584 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:607 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdcf798e929 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:00007fdcf87cc038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007fdcf7bb5fa0 RCX: 00007fdcf798e929 RDX: 0000000001000006 RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007fdcf7a10b39 R08: 0000000000000006 R09: 0000000000000000 R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fdcf7bb5fa0 R15: 00007fff64f68fd8 Allocated by task 7189: 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:4179 [inline] slab_alloc_node mm/slub.c:4228 [inline] kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4235 vm_area_alloc+0x24/0x140 mm/vma_init.c:31 __mmap_new_vma mm/vma.c:2469 [inline] __mmap_region mm/vma.c:2679 [inline] mmap_region+0xe0d/0x2080 mm/vma.c:2749 do_mmap+0xc45/0x10d0 mm/mmap.c:561 vm_mmap_pgoff+0x31b/0x4c0 mm/util.c:579 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:607 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 7194: 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:2416 [inline] slab_free_after_rcu_debug+0x129/0x2a0 mm/slub.c:4729 rcu_do_batch kernel/rcu/tree.c:2582 [inline] rcu_core+0xca5/0x1710 kernel/rcu/tree.c:2838 handle_softirqs+0x286/0x870 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 Last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548 slab_free_hook mm/slub.c:2377 [inline] slab_free mm/slub.c:4679 [inline] kmem_cache_free+0x2f6/0x400 mm/slub.c:4781 remove_vma mm/vma.c:449 [inline] vms_complete_munmap_vmas+0x6a6/0xab0 mm/vma.c:1275 __mmap_complete mm/vma.c:2535 [inline] __mmap_region mm/vma.c:2687 [inline] mmap_region+0x1221/0x2080 mm/vma.c:2749 do_mmap+0xc45/0x10d0 mm/mmap.c:561 vm_mmap_pgoff+0x31b/0x4c0 mm/util.c:579 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888028ba33c0 which belongs to the cache vm_area_struct of size 256 The buggy address is located 80 bytes inside of freed 256-byte region [ffff888028ba33c0, ffff888028ba34c0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28ba3 memcg:ffff888079f4d581 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff88814047eb40 dead000000000122 0000000000000000 raw: 0000000000000000 00000000000c000c 00000000f5000000 ffff888079f4d581 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 7181, tgid 7181 (syz.2.91), ts 155840311602, free_ts 155832927152 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704 prep_new_page mm/page_alloc.c:1712 [inline] get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419 alloc_slab_page mm/slub.c:2486 [inline] allocate_slab+0x8a/0x370 mm/slub.c:2654 new_slab mm/slub.c:2708 [inline] ___slab_alloc+0xbeb/0x1410 mm/slub.c:3890 __slab_alloc mm/slub.c:3980 [inline] __slab_alloc_node mm/slub.c:4055 [inline] slab_alloc_node mm/slub.c:4216 [inline] kmem_cache_alloc_noprof+0x283/0x3c0 mm/slub.c:4235 vm_area_dup+0x2b/0x680 mm/vma_init.c:122 __split_vma+0x1a9/0xa00 mm/vma.c:496 split_vma mm/vma.c:579 [inline] vma_modify+0x23e/0x460 mm/vma.c:1606 vma_modify_flags+0x1e8/0x230 mm/vma.c:1632 mprotect_fixup+0x400/0x9b0 mm/mprotect.c:658 do_mprotect_pkey+0x8cd/0xce0 mm/mprotect.c:832 __do_sys_mprotect mm/mprotect.c:853 [inline] __se_sys_mprotect mm/mprotect.c:850 [inline] __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:850 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 49 tgid 49 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1248 [inline] __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706 rcu_do_batch kernel/rcu/tree.c:2582 [inline] rcu_core+0xca5/0x1710 kernel/rcu/tree.c:2838 handle_softirqs+0x286/0x870 kernel/softirq.c:579 do_softirq+0xec/0x180 kernel/softirq.c:480 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:910 [inline] __dev_queue_xmit+0x1cd7/0x3a70 net/core/dev.c:4738 dev_queue_xmit include/linux/netdevice.h:3355 [inline] batadv_send_skb_packet+0x44f/0x6d0 net/batman-adv/send.c:108 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:392 [inline] batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x62f/0x7e0 net/batman-adv/bat_iv_ogm.c:1708 process_one_work kernel/workqueue.c:3239 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3322 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3403 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff888028ba3300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888028ba3380: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff888028ba3400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888028ba3480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888028ba3500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Tested on: commit: 2c923c84 Add linux-next specific files for 20250619 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=146c5370580000 kernel config: https://syzkaller.appspot.com/x/.config?x=58afc4b78b52b7e3 dashboard link: https://syzkaller.appspot.com/bug?extid=8e4be574cb8c40140a2a compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6 patch: https://syzkaller.appspot.com/x/patch.diff?x=1493f5d4580000