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bpf, sockmap: Fix potential memory leak on unlikely error case

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If skb_linearize is needed and fails we could leak a msg on the error
handling. To fix ensure we kfree the msg block before returning error.
Found during code review.

Fixes: 4363023d26 ("bpf, sockmap: Avoid failures from skb_to_sgvec when skb has frag_list")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Link: https://lore.kernel.org/bpf/20210712195546.423990-2-john.fastabend@gmail.com
This commit is contained in:
John Fastabend 2021-07-12 12:55:45 -07:00 committed by Daniel Borkmann
parent 9109165625
commit 7e6b27a691
1 changed files with 11 additions and 5 deletions
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16
net/core/skmsg.c
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@ -508,10 +508,8 @@ static int sk_psock_skb_ingress_enqueue(struct sk_buff *skb,
if (skb_linearize(skb))
return -EAGAIN;
num_sge = skb_to_sgvec(skb, msg->sg.data, 0, skb->len);
if (unlikely(num_sge < 0)) {
kfree(msg);
if (unlikely(num_sge < 0))
return num_sge;
}
copied = skb->len;
msg->sg.start = 0;
@ -530,6 +528,7 @@ static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
{
struct sock *sk = psock->sk;
struct sk_msg *msg;
int err;
/* If we are receiving on the same sock skb->sk is already assigned,
* skip memory accounting and owner transition seeing it already set
@ -548,7 +547,10 @@ static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
* into user buffers.
*/
skb_set_owner_r(skb, sk);
return sk_psock_skb_ingress_enqueue(skb, psock, sk, msg);
err = sk_psock_skb_ingress_enqueue(skb, psock, sk, msg);
if (err < 0)
kfree(msg);
return err;
}
/* Puts an skb on the ingress queue of the socket already assigned to the
@ -559,12 +561,16 @@ static int sk_psock_skb_ingress_self(struct sk_psock *psock, struct sk_buff *skb
{
struct sk_msg *msg = kzalloc(sizeof(*msg), __GFP_NOWARN | GFP_ATOMIC);
struct sock *sk = psock->sk;
int err;
if (unlikely(!msg))
return -EAGAIN;
sk_msg_init(msg);
skb_set_owner_r(skb, sk);
return sk_psock_skb_ingress_enqueue(skb, psock, sk, msg);
err = sk_psock_skb_ingress_enqueue(skb, psock, sk, msg);
if (err < 0)
kfree(msg);
return err;
}
static int sk_psock_handle_skb(struct sk_psock *psock, struct sk_buff *skb,