CVE-2021-47594

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> mptcp: never allow the PM to close a listener subflow<br /> <br /> Currently, when deleting an endpoint the netlink PM treverses<br /> all the local MPTCP sockets, regardless of their status.<br /> <br /> If an MPTCP listener socket is bound to the IP matching the<br /> delete endpoint, the listener TCP socket will be closed.<br /> That is unexpected, the PM should only affect data subflows.<br /> <br /> Additionally, syzbot was able to trigger a NULL ptr dereference<br /> due to the above:<br /> <br /> general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN<br /> KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]<br /> CPU: 1 PID: 6550 Comm: syz-executor122 Not tainted 5.16.0-rc4-syzkaller #0<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011<br /> RIP: 0010:__lock_acquire+0xd7d/0x54a0 kernel/locking/lockdep.c:4897<br /> Code: 0f 0e 41 be 01 00 00 00 0f 86 c8 00 00 00 89 05 69 cc 0f 0e e9 bd 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 3c 02 00 0f 85 f3 2f 00 00 48 81 3b 20 75 17 8f 0f 84 52 f3 ff<br /> RSP: 0018:ffffc90001f2f818 EFLAGS: 00010016<br /> RAX: dffffc0000000000 RBX: 0000000000000018 RCX: 0000000000000000<br /> RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000001<br /> RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001<br /> R10: 0000000000000000 R11: 000000000000000a R12: 0000000000000000<br /> R13: ffff88801b98d700 R14: 0000000000000000 R15: 0000000000000001<br /> FS: 00007f177cd3d700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000<br /> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> CR2: 00007f177cd1b268 CR3: 000000001dd55000 CR4: 0000000000350ee0<br /> Call Trace:<br /> <br /> lock_acquire kernel/locking/lockdep.c:5637 [inline]<br /> lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602<br /> __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]<br /> _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162<br /> finish_wait+0xc0/0x270 kernel/sched/wait.c:400<br /> inet_csk_wait_for_connect net/ipv4/inet_connection_sock.c:464 [inline]<br /> inet_csk_accept+0x7de/0x9d0 net/ipv4/inet_connection_sock.c:497<br /> mptcp_accept+0xe5/0x500 net/mptcp/protocol.c:2865<br /> inet_accept+0xe4/0x7b0 net/ipv4/af_inet.c:739<br /> mptcp_stream_accept+0x2e7/0x10e0 net/mptcp/protocol.c:3345<br /> do_accept+0x382/0x510 net/socket.c:1773<br /> __sys_accept4_file+0x7e/0xe0 net/socket.c:1816<br /> __sys_accept4+0xb0/0x100 net/socket.c:1846<br /> __do_sys_accept net/socket.c:1864 [inline]<br /> __se_sys_accept net/socket.c:1861 [inline]<br /> __x64_sys_accept+0x71/0xb0 net/socket.c:1861<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80<br /> entry_SYSCALL_64_after_hwframe+0x44/0xae<br /> RIP: 0033:0x7f177cd8b8e9<br /> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 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 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48<br /> RSP: 002b:00007f177cd3d308 EFLAGS: 00000246 ORIG_RAX: 000000000000002b<br /> RAX: ffffffffffffffda RBX: 00007f177ce13408 RCX: 00007f177cd8b8e9<br /> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003<br /> RBP: 00007f177ce13400 R08: 0000000000000000 R09: 0000000000000000<br /> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f177ce1340c<br /> R13: 00007f177cde1004 R14: 6d705f706374706d R15: 0000000000022000<br /> <br /> <br /> Fix the issue explicitly skipping MPTCP socket in TCP_LISTEN<br /> status.