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AJvYcCUjLTQ/e5e48kt8bxa+AmcNe2UjfzYeE4/cFNQNrFOIdbuHVrdZqfy8LRAOezL9q5LA8GUVsLhfjqnarDM=@vger.kernel.org X-Gm-Message-State: AOJu0Yx+yT1ZK1IAZuqi1+Vc8Pwy/A9L61HD3lwRe/H1/ifG633n3UZL HrghY4hXUNg4e0Kw/khmxJrNtp4Sq+XXpjAsHgvrgojMsQzHMtU0TQrGDGxW3L+NCaBotG/Xk1V mzhfzRWuf+oI7WUgcxSB4m013IyiuOy0kauVe8sTv6NnQFjUKL4rzDle5mcU= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:985:b0:672:a49f:1287 with SMTP id 006d021491bc7-672fc1d4a11mr1773032eaf.5.1770759812603; Tue, 10 Feb 2026 13:43:32 -0800 (PST) Date: Tue, 10 Feb 2026 13:43:32 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <698ba684.a70a0220.2c38d7.007c.GAE@google.com> Subject: [syzbot] [kernel?] KASAN: slab-use-after-free Read in futex_unqueue From: syzbot To: andrealmeid@igalia.com, dave@stgolabs.net, dvhart@infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, tglx@kernel.org Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 72c395024dac Merge tag 'docs-7.0' of git://git.kernel.org/.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=137d9b22580000 kernel config: https://syzkaller.appspot.com/x/.config?x=bf83be18dae53c93 dashboard link: https://syzkaller.appspot.com/bug?extid=6c1861115b4253e45969 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=169f8ae6580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f657fa580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/7b82c9e65868/disk-72c39502.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/e5c12e1be777/vmlinux-72c39502.xz kernel image: https://storage.googleapis.com/syzbot-assets/7a7dcee7ed8d/bzImage-72c39502.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6c1861115b4253e45969@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] BUG: KASAN: slab-use-after-free in _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 Read of size 1 at addr ffff888033ce23e0 by task syz.0.19/6039 CPU: 1 UID: 0 PID: 6039 Comm: syz.0.19 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x156/0x4c9 mm/kasan/report.c:482 kasan_report+0xdf/0x1a0 mm/kasan/report.c:595 __kasan_check_byte+0x36/0x50 mm/kasan/common.c:574 kasan_check_byte include/linux/kasan.h:402 [inline] lock_acquire kernel/locking/lockdep.c:5842 [inline] lock_acquire+0xf5/0x330 kernel/locking/lockdep.c:5825 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] futex_unqueue+0xa5/0x2c0 kernel/futex/core.c:938 __futex_wait+0x1cc/0x300 kernel/futex/waitwake.c:690 futex_wait+0xed/0x380 kernel/futex/waitwake.c:715 do_futex+0x1ef/0x350 kernel/futex/syscalls.c:130 __do_sys_futex kernel/futex/syscalls.c:207 [inline] __se_sys_futex kernel/futex/syscalls.c:188 [inline] __x64_sys_futex+0x34f/0x4d0 kernel/futex/syscalls.c:188 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6f87b9bf79 Code: Unable to access opcode bytes at 0x7f6f87b9bf4f. RSP: 002b:00007f6f889c40e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 00007f6f87e15fa8 RCX: 00007f6f87b9bf79 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6f87e15fa8 RBP: 00007f6f87e15fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6f87e16038 R14: 00007ffe2ba93260 R15: 00007ffe2ba93348 Allocated by task 6038: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __do_kmalloc_node mm/slub.c:5657 [inline] __kvmalloc_node_noprof+0x34d/0xac0 mm/slub.c:7144 futex_hash_allocate+0x40b/0x1090 kernel/futex/core.c:1812 futex_hash_allocate_default+0x2ca/0x5b0 kernel/futex/core.c:1921 copy_process+0x4eb5/0x79b0 kernel/fork.c:2344 kernel_clone+0xfc/0x930 kernel/fork.c:2654 __do_sys_clone3+0x214/0x290 kernel/fork.c:2956 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6038: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2540 [inline] slab_free mm/slub.c:6674 [inline] kfree+0x1c7/0x690 mm/slub.c:6886 futex_hash_free+0x98/0xc0 kernel/futex/core.c:1739 __mmput+0x30c/0x410 kernel/fork.c:1185 mmput+0x67/0x80 kernel/fork.c:1197 exit_mm kernel/exit.c:581 [inline] do_exit+0x78a/0x2a30 kernel/exit.c:959 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112 __do_sys_exit_group kernel/exit.c:1123 [inline] __se_sys_exit_group kernel/exit.c:1121 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1121 x64_sys_call+0x14fd/0x1510 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888033ce2000 which belongs to the cache kmalloc-cg-4k of size 4096 The buggy address is located 992 bytes inside of freed 4096-byte region [ffff888033ce2000, ffff888033ce3000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33ce0 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff888076582001 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813fe30500 dead000000000122 0000000000000000 raw: 0000000000000000 0000000080040004 00000000f5000000 ffff888076582001 head: 00fff00000000040 ffff88813fe30500 dead000000000122 0000000000000000 head: 0000000000000000 0000000080040004 00000000f5000000 ffff888076582001 head: 00fff00000000003 ffffea0000cf3801 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 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 5887, tgid 5887 (udevd), ts 101745764711, free_ts 101704527247 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1e1/0x250 mm/page_alloc.c:1884 prep_new_page mm/page_alloc.c:1892 [inline] get_page_from_freelist+0xe3d/0x2e10 mm/page_alloc.c:3945 __alloc_frozen_pages_noprof+0x26c/0x2410 mm/page_alloc.c:5240 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2486 alloc_slab_page mm/slub.c:3075 [inline] allocate_slab mm/slub.c:3248 [inline] new_slab+0x2c4/0x440 mm/slub.c:3302 ___slab_alloc+0xda3/0x1ca0 mm/slub.c:4656 __slab_alloc.isra.0+0x63/0x110 mm/slub.c:4779 __slab_alloc_node mm/slub.c:4855 [inline] slab_alloc_node mm/slub.c:5251 [inline] __do_kmalloc_node mm/slub.c:5656 [inline] __kvmalloc_node_noprof+0x749/0xac0 mm/slub.c:7144 seq_buf_alloc fs/seq_file.c:38 [inline] seq_read_iter+0x819/0x1270 fs/seq_file.c:210 kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:297 new_sync_read fs/read_write.c:493 [inline] vfs_read+0x825/0xb30 fs/read_write.c:574 ksys_read+0x12a/0x250 fs/read_write.c:717 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5933 tgid 5933 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0x822/0x1130 mm/page_alloc.c:2973 discard_slab mm/slub.c:3346 [inline] __put_partials+0x127/0x160 mm/slub.c:3886 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4953 [inline] slab_alloc_node mm/slub.c:5263 [inline] __kmalloc_cache_noprof+0x2e1/0x810 mm/slub.c:5775 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] nsim_fib4_rt_create drivers/net/netdevsim/fib.c:280 [inline] nsim_fib4_rt_insert drivers/net/netdevsim/fib.c:426 [inline] nsim_fib4_event drivers/net/netdevsim/fib.c:464 [inline] nsim_fib_event drivers/net/netdevsim/fib.c:884 [inline] nsim_fib_event_work+0xfeb/0x63b0 drivers/net/netdevsim/fib.c:1493 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3421 kthread+0x370/0x450 kernel/kthread.c:467 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 Memory state around the buggy address: ffff888033ce2280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888033ce2300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888033ce2380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888033ce2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888033ce2480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- 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. 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