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bpf: sockmap, fix skmsg recvmsg handler to track size correctly 

When converting sockmap to new skmsg generic data structures we missed
that the recvmsg handler did not correctly use sg.size and instead was
using individual elements length. The result is if a sock is closed
with outstanding data we omit the call to sk_mem_uncharge() and can
get the warning below.

[   66.728282] WARNING: CPU: 6 PID: 5783 at net/core/stream.c:206 sk_stream_kill_queues+0x1fa/0x210

To fix this correct the redirect handler to xfer the size along with
the scatterlist and also decrement the size from the recvmsg handler.
Now when a sock is closed the remaining 'size' will be decremented
with sk_mem_uncharge().

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
John Fastabend 2018-10-16 10:36:01 -07:00 committed by Daniel Borkmann
parent 9032c10e94
commit 3f4c3127d3
2 changed files with 2 additions and 0 deletions
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1
include/linux/skmsg.h
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@ -176,6 +176,7 @@ static inline void sk_msg_xfer(struct sk_msg *dst, struct sk_msg *src,
{
dst->sg.data[which] = src->sg.data[which];
dst->sg.data[which].length = size;
dst->sg.size += size;
src->sg.data[which].length -= size;
src->sg.data[which].offset += size;
}

1
net/ipv4/tcp_bpf.c
View File

@ -73,6 +73,7 @@ int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
sge->offset += copy;
sge->length -= copy;
sk_mem_uncharge(sk, copy);
msg_rx->sg.size -= copy;
if (!sge->length) {
i++;
if (i == MAX_SKB_FRAGS)