From: Eric Dumazet edumazet@google.com
commit b6f6118901d1e867ac9177bbff3b00b185bd4fdc upstream.
IPV6_ADDRFORM is able to transform IPv6 socket to IPv4 one. While this operation sounds illogical, we have to support it.
One of the things it does for TCP socket is to switch sk->sk_prot to tcp_prot.
We now have other layers playing with sk->sk_prot, so we should make sure to not interfere with them.
This patch makes sure sk_prot is the default pointer for TCP IPv6 socket.
syzbot reported : BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD a0113067 P4D a0113067 PUD a8771067 PMD 0 Oops: 0010 [#1] PREEMPT SMP KASAN CPU: 0 PID: 10686 Comm: syz-executor.0 Not tainted 5.6.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffffc9000281fce0 EFLAGS: 00010246 RAX: 1ffffffff15f48ac RBX: ffffffff8afa4560 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880a69a8f40 RBP: ffffc9000281fd10 R08: ffffffff86ed9b0c R09: ffffed1014d351f5 R10: ffffed1014d351f5 R11: 0000000000000000 R12: ffff8880920d3098 R13: 1ffff1101241a613 R14: ffff8880a69a8f40 R15: 0000000000000000 FS: 00007f2ae75db700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000000a3b85000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: inet_release+0x165/0x1c0 net/ipv4/af_inet.c:427 __sock_release net/socket.c:605 [inline] sock_close+0xe1/0x260 net/socket.c:1283 __fput+0x2e4/0x740 fs/file_table.c:280 ____fput+0x15/0x20 fs/file_table.c:313 task_work_run+0x176/0x1b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:164 [inline] prepare_exit_to_usermode+0x480/0x5b0 arch/x86/entry/common.c:195 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:278 do_syscall_64+0x11f/0x1c0 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c429 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f2ae75dac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: 0000000000000000 RBX: 00007f2ae75db6d4 RCX: 000000000045c429 RDX: 0000000000000001 RSI: 000000000000011a RDI: 0000000000000004 RBP: 000000000076bf20 R08: 0000000000000038 R09: 0000000000000000 R10: 0000000020000180 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000a9d R14: 00000000004ccfb4 R15: 000000000076bf2c Modules linked in: CR2: 0000000000000000 ---[ end trace 82567b5207e87bae ]--- RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffffc9000281fce0 EFLAGS: 00010246 RAX: 1ffffffff15f48ac RBX: ffffffff8afa4560 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880a69a8f40 RBP: ffffc9000281fd10 R08: ffffffff86ed9b0c R09: ffffed1014d351f5 R10: ffffed1014d351f5 R11: 0000000000000000 R12: ffff8880920d3098 R13: 1ffff1101241a613 R14: ffff8880a69a8f40 R15: 0000000000000000 FS: 00007f2ae75db700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000000a3b85000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot+1938db17e275e85dc328@syzkaller.appspotmail.com Cc: Daniel Borkmann daniel@iogearbox.net Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/ipv6/ipv6_sockglue.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -184,9 +184,15 @@ static int do_ipv6_setsockopt(struct soc retv = -EBUSY; break; } - } else if (sk->sk_protocol != IPPROTO_TCP) + } else if (sk->sk_protocol == IPPROTO_TCP) { + if (sk->sk_prot != &tcpv6_prot) { + retv = -EBUSY; + break; + } + break; + } else { break; - + } if (sk->sk_state != TCP_ESTABLISHED) { retv = -ENOTCONN; break;