From: Sungwoo Kim iam@sung-woo.kim
commit 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 upstream.
l2cap_sock_release(sk) frees sk. However, sk's children are still alive and point to the already free'd sk's address. To fix this, l2cap_sock_release(sk) also cleans sk's children.
================================================================== BUG: KASAN: use-after-free in l2cap_sock_ready_cb+0xb7/0x100 net/bluetooth/l2cap_sock.c:1650 Read of size 8 at addr ffff888104617aa8 by task kworker/u3:0/276
CPU: 0 PID: 276 Comm: kworker/u3:0 Not tainted 6.2.0-00001-gef397bd4d5fb-dirty #59 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Workqueue: hci2 hci_rx_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x72/0x95 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:306 [inline] print_report+0x175/0x478 mm/kasan/report.c:417 kasan_report+0xb1/0x130 mm/kasan/report.c:517 l2cap_sock_ready_cb+0xb7/0x100 net/bluetooth/l2cap_sock.c:1650 l2cap_chan_ready+0x10e/0x1e0 net/bluetooth/l2cap_core.c:1386 l2cap_config_req+0x753/0x9f0 net/bluetooth/l2cap_core.c:4480 l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:5739 [inline] l2cap_sig_channel net/bluetooth/l2cap_core.c:6509 [inline] l2cap_recv_frame+0xe2e/0x43c0 net/bluetooth/l2cap_core.c:7788 l2cap_recv_acldata+0x6ed/0x7e0 net/bluetooth/l2cap_core.c:8506 hci_acldata_packet net/bluetooth/hci_core.c:3813 [inline] hci_rx_work+0x66e/0xbc0 net/bluetooth/hci_core.c:4048 process_one_work+0x4ea/0x8e0 kernel/workqueue.c:2289 worker_thread+0x364/0x8e0 kernel/workqueue.c:2436 kthread+0x1b9/0x200 kernel/kthread.c:376 ret_from_fork+0x2c/0x50 arch/x86/entry/entry_64.S:308 </TASK>
Allocated by task 288: kasan_save_stack+0x22/0x50 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x82/0x90 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:968 [inline] __kmalloc+0x5a/0x140 mm/slab_common.c:981 kmalloc include/linux/slab.h:584 [inline] sk_prot_alloc+0x113/0x1f0 net/core/sock.c:2040 sk_alloc+0x36/0x3c0 net/core/sock.c:2093 l2cap_sock_alloc.constprop.0+0x39/0x1c0 net/bluetooth/l2cap_sock.c:1852 l2cap_sock_create+0x10d/0x220 net/bluetooth/l2cap_sock.c:1898 bt_sock_create+0x183/0x290 net/bluetooth/af_bluetooth.c:132 __sock_create+0x226/0x380 net/socket.c:1518 sock_create net/socket.c:1569 [inline] __sys_socket_create net/socket.c:1606 [inline] __sys_socket_create net/socket.c:1591 [inline] __sys_socket+0x112/0x200 net/socket.c:1639 __do_sys_socket net/socket.c:1652 [inline] __se_sys_socket net/socket.c:1650 [inline] __x64_sys_socket+0x40/0x50 net/socket.c:1650 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3f/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x72/0xdc
Freed by task 288: kasan_save_stack+0x22/0x50 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:523 ____kasan_slab_free mm/kasan/common.c:236 [inline] ____kasan_slab_free mm/kasan/common.c:200 [inline] __kasan_slab_free+0x10a/0x190 mm/kasan/common.c:244 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1781 [inline] slab_free_freelist_hook mm/slub.c:1807 [inline] slab_free mm/slub.c:3787 [inline] __kmem_cache_free+0x88/0x1f0 mm/slub.c:3800 sk_prot_free net/core/sock.c:2076 [inline] __sk_destruct+0x347/0x430 net/core/sock.c:2168 sk_destruct+0x9c/0xb0 net/core/sock.c:2183 __sk_free+0x82/0x220 net/core/sock.c:2194 sk_free+0x7c/0xa0 net/core/sock.c:2205 sock_put include/net/sock.h:1991 [inline] l2cap_sock_kill+0x256/0x2b0 net/bluetooth/l2cap_sock.c:1257 l2cap_sock_release+0x1a7/0x220 net/bluetooth/l2cap_sock.c:1428 __sock_release+0x80/0x150 net/socket.c:650 sock_close+0x19/0x30 net/socket.c:1368 __fput+0x17a/0x5c0 fs/file_table.c:320 task_work_run+0x132/0x1c0 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x113/0x120 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x21/0x50 kernel/entry/common.c:296 do_syscall_64+0x4c/0x90 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x72/0xdc
The buggy address belongs to the object at ffff888104617800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 680 bytes inside of 1024-byte region [ffff888104617800, ffff888104617c00)
The buggy address belongs to the physical page: page:00000000dbca6a80 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888104614000 pfn:0x104614 head:00000000dbca6a80 order:2 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0 flags: 0x200000000010200(slab|head|node=0|zone=2) raw: 0200000000010200 ffff888100041dc0 ffffea0004212c10 ffffea0004234b10 raw: ffff888104614000 0000000000080002 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff888104617980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888104617a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888104617a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff888104617b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888104617b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
Ack: This bug is found by FuzzBT with a modified Syzkaller. Other contributors are Ruoyu Wu and Hui Peng. Signed-off-by: Sungwoo Kim iam@sung-woo.kim Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/bluetooth/l2cap_sock.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -45,6 +45,7 @@ static const struct proto_ops l2cap_sock static void l2cap_sock_init(struct sock *sk, struct sock *parent); static struct sock *l2cap_sock_alloc(struct net *net, struct socket *sock, int proto, gfp_t prio, int kern); +static void l2cap_sock_cleanup_listen(struct sock *parent);
bool l2cap_is_socket(struct socket *sock) { @@ -1206,6 +1207,7 @@ static int l2cap_sock_release(struct soc if (!sk) return 0;
+ l2cap_sock_cleanup_listen(sk); bt_sock_unlink(&l2cap_sk_list, sk);
err = l2cap_sock_shutdown(sock, 2);