From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f72.google.com (mail-oa1-f72.google.com [209.85.160.72]) (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 8BEAA3DCDA4 for ; Mon, 10 Aug 2026 13:22:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.72 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786368153; cv=none; b=q7rqlwXguJp5viYhNrFFByrGTW8ZDXMbtaBsadEyJWOKufH92KCb3rgBFCEptdC1guEZY8AXi4kt8mCGV9WvcwTgJ9s1GhqWSMwqCo5nVdEF4SMPUTMSF2xuhZJPUzkA0lbSaRCD/X5fPyrOBhoPuv1RyoceDRNCt5alqDeoi34= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786368153; c=relaxed/simple; bh=0j0LkihhU2HfDwCxV3ZnnCFJ9C3P29IZwcnP1B+/jc4=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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2002:a4a:ee14:0:b0:6ac:b80e:76b0 with SMTP id 006d021491bc7-6b041eb0f8bmr10576185eaf.3.1786368150395; Mon, 10 Aug 2026 06:22:30 -0700 (PDT) Date: Mon, 10 Aug 2026 06:22:30 -0700 In-Reply-To: <6a7919fe.9c11d2ce.289b96.00df.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a79d096.9c11d2ce.289b96.00ed.GAE@google.com> Subject: Re: [syzbot] [afs?] [net?] KASAN: slab-use-after-free Read in rxrpc_destroy_all_peers From: syzbot To: davem@davemloft.net, dhowells@redhat.com, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org, marc.dionne@auristor.com, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: db2ddb871435 Linux 7.2-rc7 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=152cd079580000 kernel config: https://syzkaller.appspot.com/x/.config?x=c44651ea7dd2f307 dashboard link: https://syzkaller.appspot.com/bug?extid=c876adfab6362679008c compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17e35132580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c876adfab6362679008c@syzkaller.appspotmail.com rxrpc: Leaked peer 4dfc {1} 127.0.0.1:8051 rxrpc: Leaked peer 5009 {1} 127.0.0.1:8167 rxrpc: Leaked peer 5726 {1} 127.0.0.1:8581 rxrpc: Leaked peer 5523 {0} 127.0.0.1:8374 ================================================================== BUG: KASAN: slab-use-after-free in rxrpc_destroy_all_peers+0x1ce/0x1d0 net/rxrpc/peer_object.c:461 Read of size 8 at addr ffff888054f70c20 by task kworker/u8:3/48 CPU: 0 UID: 0 PID: 48 Comm: kworker/u8:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: netns cleanup_net 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+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595 rxrpc_destroy_all_peers+0x1ce/0x1d0 net/rxrpc/peer_object.c:461 rxrpc_exit_net+0x83/0xc0 net/rxrpc/net_ns.c:114 ops_exit_list net/core/net_namespace.c:199 [inline] ops_undo_list+0x2ee/0xab0 net/core/net_namespace.c:252 cleanup_net+0x499/0x920 net/core/net_namespace.c:702 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Allocated by task 6240: 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] __kmalloc_cache_noprof+0x2e5/0x6c0 mm/slub.c:5489 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] rxrpc_alloc_peer+0xa7/0x400 net/rxrpc/peer_object.c:229 rxrpc_create_peer net/rxrpc/peer_object.c:293 [inline] rxrpc_lookup_peer+0x168/0x680 net/rxrpc/peer_object.c:354 rxrpc_kernel_lookup_peer+0xa8/0xe0 net/rxrpc/af_rxrpc.c:285 afs_merge_fs_addr4+0x1cd/0x4c0 fs/afs/addr_list.c:300 afs_parse_text_addrs+0x655/0xa10 fs/afs/addr_list.c:220 afs_alloc_cell fs/afs/cell.c:181 [inline] afs_lookup_cell+0xbb6/0x1940 fs/afs/cell.c:273 afs_proc_cells_write+0x2a3/0x3a0 fs/afs/proc.c:125 proc_simple_write+0x10e/0x1a0 fs/proc/generic.c:843 pde_write fs/proc/inode.c:330 [inline] proc_reg_write+0x240/0x330 fs/proc/inode.c:342 vfs_write+0x2aa/0x1050 fs/read_write.c:685 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 16: 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:2677 [inline] __rcu_free_sheaf_prepare+0x5d/0x2f0 mm/slub.c:2928 rcu_free_sheaf+0x1a/0xe0 mm/slub.c:5978 rcu_do_batch kernel/rcu/tree.c:2645 [inline] rcu_core+0x5a2/0x10d0 kernel/rcu/tree.c:2897 handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_call_function_single arch/x86/kernel/smp.c:267 [inline] sysvec_call_function_single+0xa3/0xc0 arch/x86/kernel/smp.c:267 asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:681 The buggy address belongs to the object at ffff888054f70c00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 32 bytes inside of freed 512-byte region [ffff888054f70c00, ffff888054f70e00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x54f70 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813fe21c80 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe21c80 dead000000000100 dead000000000122 head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6240, tgid 6240 (syz-executor166), ts 101070694469, free_ts 79760049897 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859 prep_new_page mm/page_alloc.c:1867 [inline] get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304 alloc_slab_page mm/slub.c:3266 [inline] allocate_slab mm/slub.c:3380 [inline] new_slab+0xa2/0x640 mm/slub.c:3426 refill_objects+0xe3/0x410 mm/slub.c:7310 refill_sheaf mm/slub.c:2804 [inline] __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675 alloc_from_pcs mm/slub.c:4773 [inline] slab_alloc_node mm/slub.c:4905 [inline] __kmalloc_cache_noprof+0x479/0x6c0 mm/slub.c:5485 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] rxrpc_alloc_peer+0xa7/0x400 net/rxrpc/peer_object.c:229 rxrpc_create_peer net/rxrpc/peer_object.c:293 [inline] rxrpc_lookup_peer+0x168/0x680 net/rxrpc/peer_object.c:354 rxrpc_kernel_lookup_peer+0xa8/0xe0 net/rxrpc/af_rxrpc.c:285 afs_merge_fs_addr4+0x1cd/0x4c0 fs/afs/addr_list.c:300 afs_parse_text_addrs+0x655/0xa10 fs/afs/addr_list.c:220 afs_alloc_cell fs/afs/cell.c:181 [inline] afs_lookup_cell+0xbb6/0x1940 fs/afs/cell.c:273 afs_proc_cells_write+0x2a3/0x3a0 fs/afs/proc.c:125 proc_simple_write+0x10e/0x1a0 fs/proc/generic.c:843 pde_write fs/proc/inode.c:330 [inline] proc_reg_write+0x240/0x330 fs/proc/inode.c:342 page last free pid 5674 tgid 5674 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] free_pages_prepare+0x586/0xd80 mm/page_alloc.c:1451 __free_contig_range_common+0x14f/0x250 mm/page_alloc.c:6897 __free_contig_range mm/page_alloc.c:6942 [inline] free_pages_bulk+0x12a/0x200 mm/page_alloc.c:5257 vm_area_free_pages+0xad/0x2b0 mm/vmalloc.c:3461 vfree mm/vmalloc.c:3510 [inline] vfree+0x107/0x750 mm/vmalloc.c:3484 kcov_put kernel/kcov.c:447 [inline] kcov_put kernel/kcov.c:443 [inline] kcov_close+0x34/0x60 kernel/kcov.c:554 __fput+0x3ff/0xb50 fs/file_table.c:512 task_work_run+0x150/0x240 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x951/0x2ae0 kernel/exit.c:1009 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152 get_signal+0x1ec7/0x21e0 kernel/signal.c:3046 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x139/0x6f0 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888054f70b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888054f70b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888054f70c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888054f70c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888054f70d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- 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.