From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f206.google.com (mail-il1-f206.google.com [209.85.166.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E57AE1519B4 for ; Sat, 16 Aug 2025 03:07:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.206 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755313656; cv=none; b=uL5CwyFvSzgR67ofKXNVjMduwj2iWv4H8GjxA1TJ4Isr1+DlofRWVbGfqH5roTNxiblfrlZFTRKyttw+BDNIgO3hSE8Dll/Hh+G1b0nmK1JnqjGwb3BLP04UR6+nD/O4CVELdQWw2dxGkR6VaG7MwSyYXagtUTNkHo/Rj9HDxC8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755313656; c=relaxed/simple; bh=pRVFIV3TJ23nyiDRrtjxtLK9GH2Fvg8SKVHheIUhTSE=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; 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List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:1a85:b0:3e5:4715:ebdc with SMTP id e9e14a558f8ab-3e57e8244damr79813405ab.8.1755313654082; Fri, 15 Aug 2025 20:07:34 -0700 (PDT) Date: Fri, 15 Aug 2025 20:07:34 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <689ff5f6.050a0220.e29e5.0030.GAE@google.com> Subject: [syzbot] [mm?] KASAN: slab-use-after-free Read in mremap From: syzbot To: Liam.Howlett@oracle.com, akpm@linux-foundation.org, jannh@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, pfalcato@suse.de, syzkaller-bugs@googlegroups.com, vbabka@suse.cz Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 931e46dcbc7e Add linux-next specific files for 20250814 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=16a66af0580000 kernel config: https://syzkaller.appspot.com/x/.config?x=bb7fbecfa2364d1c dashboard link: https://syzkaller.appspot.com/bug?extid=4e221abf50259362f4f4 compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11fb3c34580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173c2dbc580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/68e3ffeee4c1/disk-931e46dc.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/3cc40de4a0c3/vmlinux-931e46dc.xz kernel image: https://storage.googleapis.com/syzbot-assets/aed3e4f6a518/bzImage-931e46dc.xz The issue was bisected to: commit d50dabff4d1f2c815b2faf184f5d6db40596e2cc Author: Lorenzo Stoakes Date: Sun Aug 3 11:11:22 2025 +0000 mm/mremap: catch invalid multi VMA moves earlier bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16fadda2580000 final oops: https://syzkaller.appspot.com/x/report.txt?x=15fadda2580000 console output: https://syzkaller.appspot.com/x/log.txt?x=11fadda2580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+4e221abf50259362f4f4@syzkaller.appspotmail.com Fixes: d50dabff4d1f ("mm/mremap: catch invalid multi VMA moves earlier") ================================================================== BUG: KASAN: slab-use-after-free in vma_multi_allowed mm/mremap.c:1623 [inline] BUG: KASAN: slab-use-after-free in remap_move mm/mremap.c:1884 [inline] BUG: KASAN: slab-use-after-free in do_mremap mm/mremap.c:1923 [inline] BUG: KASAN: slab-use-after-free in __do_sys_mremap mm/mremap.c:1987 [inline] BUG: KASAN: slab-use-after-free in __se_sys_mremap+0xb33/0x1150 mm/mremap.c:1955 Read of size 8 at addr ffff888074738558 by task syz.0.59/6077 CPU: 1 UID: 0 PID: 6077 Comm: syz.0.59 Not tainted 6.17.0-rc1-next-20250814-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 vma_multi_allowed mm/mremap.c:1623 [inline] remap_move mm/mremap.c:1884 [inline] do_mremap mm/mremap.c:1923 [inline] __do_sys_mremap mm/mremap.c:1987 [inline] __se_sys_mremap+0xb33/0x1150 mm/mremap.c:1955 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: 0033:0x7f7fd678ebe9 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:00007fff51cbeae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000019 RAX: ffffffffffffffda RBX: 00007f7fd69b5fa0 RCX: 00007f7fd678ebe9 RDX: 0000000000002000 RSI: 0000000000002000 RDI: 0000200000041000 RBP: 00007f7fd6811e19 R08: 00002000004c3000 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7fd69b5fa0 R14: 00007f7fd69b5fa0 R15: 0000000000000005 Allocated by task 5972: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 unpoison_slab_object mm/kasan/common.c:339 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:365 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4180 [inline] slab_alloc_node mm/slub.c:4229 [inline] kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4236 vm_area_dup+0x2b/0x680 mm/vma_init.c:122 dup_mmap+0x90c/0x1ac0 mm/mmap.c:1780 dup_mm kernel/fork.c:1485 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1537 copy_process+0x1706/0x3c00 kernel/fork.c:2175 kernel_clone+0x21e/0x840 kernel/fork.c:2605 __do_sys_clone kernel/fork.c:2748 [inline] __se_sys_clone kernel/fork.c:2732 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2732 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 2999: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2417 [inline] slab_free_after_rcu_debug+0x129/0x2a0 mm/slub.c:4730 rcu_do_batch kernel/rcu/tree.c:2605 [inline] rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861 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 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_nc_purge_paths+0x318/0x3b0 net/batman-adv/network-coding.c:471 batadv_nc_worker+0x328/0x610 net/batman-adv/network-coding.c:720 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559 slab_free_hook mm/slub.c:2378 [inline] slab_free mm/slub.c:4680 [inline] kmem_cache_free+0x2f6/0x400 mm/slub.c:4782 remove_vma mm/vma.c:468 [inline] vms_complete_munmap_vmas+0x626/0x8a0 mm/vma.c:1293 do_vmi_align_munmap+0x358/0x420 mm/vma.c:1536 do_vmi_munmap+0x253/0x2e0 mm/vma.c:1584 do_munmap+0xe1/0x140 mm/mmap.c:1068 mremap_to+0x2df/0x7a0 mm/mremap.c:1372 remap_move mm/mremap.c:1879 [inline] do_mremap mm/mremap.c:1923 [inline] __do_sys_mremap mm/mremap.c:1987 [inline] __se_sys_mremap+0xadf/0x1150 mm/mremap.c:1955 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 ffff888074738500 which belongs to the cache vm_area_struct of size 256 The buggy address is located 88 bytes inside of freed 256-byte region [ffff888074738500, ffff888074738600) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x74738 memcg:ffff888030d7f981 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff88801bed5b40 dead000000000100 dead000000000122 raw: 0000000000000000 00000000000c000c 00000000f5000000 ffff888030d7f981 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 5248, tgid 5248 (udevd), ts 24347982328, free_ts 24338159697 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:2487 [inline] allocate_slab+0x8a/0x370 mm/slub.c:2655 new_slab mm/slub.c:2709 [inline] ___slab_alloc+0xbeb/0x1410 mm/slub.c:3891 __slab_alloc mm/slub.c:3981 [inline] __slab_alloc_node mm/slub.c:4056 [inline] slab_alloc_node mm/slub.c:4217 [inline] kmem_cache_alloc_noprof+0x283/0x3c0 mm/slub.c:4236 vm_area_dup+0x2b/0x680 mm/vma_init.c:122 dup_mmap+0x90c/0x1ac0 mm/mmap.c:1780 dup_mm kernel/fork.c:1485 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1537 copy_process+0x1706/0x3c00 kernel/fork.c:2175 kernel_clone+0x21e/0x840 kernel/fork.c:2605 __do_sys_clone kernel/fork.c:2748 [inline] __se_sys_clone kernel/fork.c:2732 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2732 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 23 tgid 23 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895 pagetable_free include/linux/mm.h:2917 [inline] pagetable_dtor_free include/linux/mm.h:3015 [inline] __tlb_remove_table+0x2d2/0x3b0 include/asm-generic/tlb.h:220 __tlb_remove_table_free mm/mmu_gather.c:227 [inline] tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:290 rcu_do_batch kernel/rcu/tree.c:2605 [inline] rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861 handle_softirqs+0x286/0x870 kernel/softirq.c:579 run_ksoftirqd+0x9b/0x100 kernel/softirq.c:968 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 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: ffff888074738400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888074738480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff888074738500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888074738580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888074738600: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup