[PATCH net v2 2/5] vsock/bpf: return early if transport is not assigned
From: Stefano Garzarella <sgarzare@redhat.com>
Date: 2025-01-10 08:35:30
Also in:
bpf, kvm, lkml, stable, virtualization
Subsystem:
networking [general], the rest, vm sockets (af_vsock) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Stefano Garzarella
Some of the core functions can only be called if the transport
has been assigned.
As Michal reported, a socket might have the transport at NULL,
for example after a failed connect(), causing the following trace:
BUG: kernel NULL pointer dereference, address: 00000000000000a0
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 12faf8067 P4D 12faf8067 PUD 113670067 PMD 0
Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 15 UID: 0 PID: 1198 Comm: a.out Not tainted 6.13.0-rc2+
RIP: 0010:vsock_connectible_has_data+0x1f/0x40
Call Trace:
vsock_bpf_recvmsg+0xca/0x5e0
sock_recvmsg+0xb9/0xc0
__sys_recvfrom+0xb3/0x130
__x64_sys_recvfrom+0x20/0x30
do_syscall_64+0x93/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
So we need to check the `vsk->transport` in vsock_bpf_recvmsg(),
especially for connected sockets (stream/seqpacket) as we already
do in __vsock_connectible_recvmsg().
Fixes: 634f1a7110b4 ("vsock: support sockmap")
Cc: stable@vger.kernel.org
Reported-by: Michal Luczaj <redacted>
Closes: https://lore.kernel.org/netdev/5ca20d4c-1017-49c2-9516-f6f75fd331e9@rbox.co/ (local)
Tested-by: Michal Luczaj <redacted>
Reported-by: syzbot+3affdbfc986ecd9200fd@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/677f84a8.050a0220.25a300.01b3.GAE@google.com/ (local)
Tested-by: syzbot+3affdbfc986ecd9200fd@syzkaller.appspotmail.com
Reviewed-by: Hyunwoo Kim <redacted>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Luigi Leonardi <redacted>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
net/vmw_vsock/vsock_bpf.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/net/vmw_vsock/vsock_bpf.c b/net/vmw_vsock/vsock_bpf.c
index 4aa6e74ec295..f201d9eca1df 100644
--- a/net/vmw_vsock/vsock_bpf.c
+++ b/net/vmw_vsock/vsock_bpf.c@@ -77,6 +77,7 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags, int *addr_len) { struct sk_psock *psock; + struct vsock_sock *vsk; int copied; psock = sk_psock_get(sk);
@@ -84,6 +85,13 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, return __vsock_recvmsg(sk, msg, len, flags); lock_sock(sk); + vsk = vsock_sk(sk); + + if (!vsk->transport) { + copied = -ENODEV; + goto out; + } + if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) { release_sock(sk); sk_psock_put(sk, psock);
@@ -108,6 +116,7 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, copied = sk_msg_recvmsg(sk, psock, msg, len, flags); } +out: release_sock(sk); sk_psock_put(sk, psock);
--
2.47.1