Hello, I found a bug titled ˇ° KASAN: slab-out-of-bounds Write in sco_conn_put ˇ±with modified syzkaller in the lasted upstream related to bluetooth subsystem. If you fix this issue, please add the following tag to the commit: Reported-by: Jianzhou Zhao<xnxc22xnxc22@xxxxxx> xingwei lee <xrivendell7@xxxxxxxxx> Zhizhuo Tang <strforexctzzchange@xxxxxxxxxxx> ------------[ cut here ]------------ TITLE: BUG: KASAN: slab-out-of-bounds Write in sco_conn_put ================================================================== ================================================================= BUG: KASAN: slab-out-of-bounds in sco_conn_free net/bluetooth/sco.c:87 [inline] BUG: KASAN: slab-out-of-bounds in kref_put include/linux/kref.h:65 [inline] BUG: KASAN: slab-out-of-bounds in sco_conn_put+0x479/0x4d0 net/bluetooth/sco.c:107 Write of size 8 at addr ffff888028b075a0 by task syz-executor/12481 CPU: 1 UID: 0 PID: 12481 Comm: syz-executor Not tainted 6.14.0-rc5-dirty #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: <task> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc1/0x630 mm/kasan/report.c:521 kasan_report+0xbd/0xf0 mm/kasan/report.c:634 sco_conn_free net/bluetooth/sco.c:87 [inline] kref_put include/linux/kref.h:65 [inline] sco_conn_put+0x479/0x4d0 net/bluetooth/sco.c:107 sco_conn_del+0x25f/0x2f0 net/bluetooth/sco.c:263 hci_disconn_cfm include/net/bluetooth/hci_core.h:2069 [inline] hci_conn_hash_flush+0x44b/0x780 net/bluetooth/hci_conn.c:2698 hci_dev_close_sync+0x5b0/0x11a0 net/bluetooth/hci_sync.c:5197 hci_dev_do_close+0x31/0xa0 net/bluetooth/hci_core.c:482 hci_unregister_dev+0x213/0x630 net/bluetooth/hci_core.c:2677 vhci_release+0x7a/0xf0 drivers/bluetooth/hci_vhci.c:664 __fput+0x3ff/0xb50 fs/file_table.c:464 task_work_run+0x169/0x260 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xade/0x2d00 kernel/exit.c:938 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087 get_signal+0x2278/0x2540 kernel/signal.c:3036 arch_do_signal_or_restart+0x81/0x7d0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218 do_syscall_64+0xd8/0x250 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd514dabbb6 Code: Unable to access opcode bytes at 0x7fd514dabb8c. RSP: 002b:00007fff2dbb8ac0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: 0000000000000028 RBX: 00007fd515af4620 RCX: 00007fd514dabbb6 RDX: 0000000000000028 RSI: 00007fd515af4670 RDI: 0000000000000003 RBP: 0000000000000001 R08: 00007fff2dbb8b1c R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007fd515af4670 R14: 0000000000000003 R15: 0000000000000000 </task> Allocated by task 13326: kasan_save_stack+0x24/0x50 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 kmalloc_noprof include/linux/slab.h:901 [inline] kzalloc_noprof include/linux/slab.h:1037 [inline] rxrpc_alloc_connection+0x91/0x780 net/rxrpc/conn_object.c:62 rxrpc_prealloc_service_connection+0x28/0x3a0 net/rxrpc/conn_service.c:123 rxrpc_service_prealloc_one+0x2c5/0xf20 net/rxrpc/call_accept.c:87 rxrpc_kernel_charge_accept+0xd8/0x120 net/rxrpc/call_accept.c:475 afs_charge_preallocation+0xbe/0x310 fs/afs/rxrpc.c:739 afs_open_socket+0x290/0x360 fs/afs/rxrpc.c:95 afs_net_init+0x966/0xc60 fs/afs/main.c:123 ops_init+0x1df/0x5f0 net/core/net_namespace.c:138 setup_net+0x21f/0x870 net/core/net_namespace.c:362 copy_net_ns+0x2aa/0x600 net/core/net_namespace.c:516 create_new_namespaces+0x3f6/0xaf0 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc0/0x200 kernel/nsproxy.c:228 ksys_unshare+0x462/0xa00 kernel/fork.c:3342 __do_sys_unshare kernel/fork.c:3413 [inline] __se_sys_unshare kernel/fork.c:3411 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3411 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888028b07000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 304 bytes to the right of allocated 1136-byte region [ffff888028b07000, ffff888028b07470) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28b00 head: order:3 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 ffff88801b042000 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b042000 dead000000000100 dead000000000122 head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0000a2c001 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 9488, tgid 9488 (syz-executor), ts 260505925503, free_ts 198428693595 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x193/0x1c0 mm/page_alloc.c:1551 prep_new_page mm/page_alloc.c:1559 [inline] get_page_from_freelist+0xe4e/0x2b20 mm/page_alloc.c:3477 __alloc_frozen_pages_noprof+0x219/0x21f0 mm/page_alloc.c:4739 alloc_pages_mpol+0x1f2/0x540 mm/mempolicy.c:2270 alloc_slab_page mm/slub.c:2423 [inline] allocate_slab mm/slub.c:2587 [inline] new_slab+0x248/0x350 mm/slub.c:2640 ___slab_alloc+0xbb2/0x1810 mm/slub.c:3826 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3916 __slab_alloc_node mm/slub.c:3991 [inline] slab_alloc_node mm/slub.c:4152 [inline] __kmalloc_cache_noprof+0x280/0x410 mm/slub.c:4320 kmalloc_noprof include/linux/slab.h:901 [inline] rtnl_newlink+0xd0/0x1cf0 net/core/rtnetlink.c:3922 rtnetlink_rcv_msg+0x9e3/0xfb0 net/core/rtnetlink.c:6912 netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2533 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x544/0x800 net/netlink/af_netlink.c:1338 netlink_sendmsg+0x8a5/0xd80 net/netlink/af_netlink.c:1882 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:733 [inline] __sys_sendto+0x4fc/0x570 net/socket.c:2187 __do_sys_sendto net/socket.c:2194 [inline] __se_sys_sendto net/socket.c:2190 [inline] __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2190 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 page last free pid 9305 tgid 9305 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1127 [inline] free_frozen_pages+0x718/0xfd0 mm/page_alloc.c:2660 __put_partials+0x154/0x170 mm/slub.c:3153 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x50/0x120 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x67/0x90 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_noprof+0x1c3/0x530 mm/slub.c:4306 kmalloc_noprof include/linux/slab.h:905 [inline] tomoyo_realpath_from_path+0xc3/0x600 security/tomoyo/realpath.c:251 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_perm+0x236/0x430 security/tomoyo/file.c:822 security_inode_getattr+0x122/0x2b0 security/security.c:2377 vfs_getattr fs/stat.c:243 [inline] vfs_fstat+0x50/0xc0 fs/stat.c:265 __do_sys_newfstat+0x84/0x100 fs/stat.c:542 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888028b07480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888028b07500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888028b07580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888028b07600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888028b07680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== ================================================================== I use the same kernel as syzbot instance upstream: 7eb172143d5508b4da468ed59ee857c6e5e01da6 kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&amp;amp;x=da4b04ae798b7ef6 compiler: gcc version 11.4.0 =============================================================================== Unfortunately, the modified syzkaller does not generate an effective repeat program. The following is my analysis of the bug and repair suggestions, hoping to help with the repair of the bug: Root cause: UAF (Use-After-Free) : When the socket pointed to conn->sk has been released, but the sco_conn structure still retains its pointer, the overreach is triggered when the sco_pi(conn->sk) is accessed. Lifecycle management flaw: Bidirectional references of Socket and SCO connections do not synchronize the release order correctly, resulting in access to freed socket memory. ### Repair suggestions 1. Actively disconnect the connection reference when the Socket is released.Modify the Socket release logic to ensure that the associated conn->sk pointer is cleared during destruction to avoid subsequent access. // net/bluetooth/sco.c static void sco_sock_destruct(struct sock *sk) { ++ struct sco_conn *conn = sco_pi(sk)->conn; -- BT_DBG("sk %p", sk); ++ BT_DBG("sk %p conn %p", sk, conn); -- sco_conn_put(sco_pi(sk)->conn); ++ if (conn) { ++ sco_pi(sk)->conn = NULL; // Disconnect the Socket from the conn reference ++ sco_conn_put(conn); ++ } skb_queue_purge(&sk->sk_receive_queue); skb_queue_purge(&sk->sk_write_queue); } 2. Ensure that Socket references are cleared when SCO connections are released.The validity of conn->sk is no longer relied on in sco_conn_free because the association was actively disassociated when the Socket was released. net/bluetooth/sco.c static void sco_conn_free(struct kref *ref) { struct sco_conn *conn = container_of(ref, struct sco_conn, ref); BT_DBG("conn %p", conn); ++ //Access to conn->sk was removed, and the Socket cleaned itself -- if (conn->sk) -- sco_pi(conn->sk)->conn = NULL; if (conn->hcon) { conn->hcon->sco_data = NULL; hci_conn_drop(conn->hcon); } /* Ensure no more work items will run since hci_conn has been dropped */ disable_delayed_work_sync(&conn->timeout_work); kfree(conn); } 3.Adjust the connection disconnection logical sequence.In sco_conn_del, disconnect the Socket from the connection before releasing resources. net/bluetooth/sco.c static void sco_conn_del(struct hci_conn *hcon, int err) { struct sco_conn *conn = hcon->sco_data; struct sock *sk; conn = sco_conn_hold_unless_zero(conn); if (!conn) return; BT_DBG("hcon %p conn %p, err %d", hcon, conn, err); sco_conn_lock(conn); sk = sco_sock_hold(conn); sco_conn_unlock(conn); sco_conn_put(conn); if (!sk) { sco_conn_put(conn); return; } /* Kill socket */ lock_sock(sk); sco_sock_clear_timer(sk); sco_chan_del(sk, err); release_sock(sk); sock_put(sk); ++ conn->sk = NULL; // Ensure that conn no longer holds processed SKS } ========================================================================= I hope it helps. Best regards Jianzhou Zhao xingwei lee Zhizhuo Tang</strforexctzzchange@xxxxxxxxxxx></xrivendell7@xxxxxxxxx></xnxc22xnxc22@xxxxxx>