Commit 3cc9a472 authored by John Fastabend's avatar John Fastabend Committed by Alexei Starovoitov

bpf: sockmap, fix scatterlist update on error path in send with apply

When the call to do_tcp_sendpage() fails to send the complete block
requested we either retry if only a partial send was completed or
abort if we receive a error less than or equal to zero. Before
returning though we must update the scatterlist length/offset to
account for any partial send completed.

Before this patch we did this at the end of the retry loop, but
this was buggy when used while applying a verdict to fewer bytes
than in the scatterlist. When the scatterlist length was being set
we forgot to account for the apply logic reducing the size variable.
So the result was we chopped off some bytes in the scatterlist without
doing proper cleanup on them. This results in a WARNING when the
sock is tore down because the bytes have previously been charged to
the socket but are never uncharged.

The simple fix is to simply do the accounting inside the retry loop
subtracting from the absolute scatterlist values rather than trying
to accumulate the totals and subtract at the end.
Reported-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0f58e58e
......@@ -326,6 +326,9 @@ static int bpf_tcp_push(struct sock *sk, int apply_bytes,
if (ret > 0) {
if (apply)
apply_bytes -= ret;
sg->offset += ret;
sg->length -= ret;
size -= ret;
offset += ret;
if (uncharge)
......@@ -333,8 +336,6 @@ static int bpf_tcp_push(struct sock *sk, int apply_bytes,
goto retry;
}
sg->length = size;
sg->offset = offset;
return ret;
}
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment