From: Dan Aloni dan@kernelim.com
[ Upstream commit ac9645c87380e39a8fa87a1b51721efcdea89dbf ]
When receiving pages data, return value 'ret' when positive includes `buf->page_base`, so we should subtract that before it is used for changing `offset` and comparing against `want`.
This was discovered on the very rare cases where the server returned a chunk of bytes that when added to the already received amount of bytes for the pages happened to match the current `recv.len`, for example on this case:
buf->page_base : 258356 actually received from socket: 1740 ret : 260096 want : 260096
In this case neither of the two 'if ... goto out' trigger, and we continue to tail parsing.
Worth to mention that the ensuing EMSGSIZE from the continued execution of `xs_read_xdr_buf` may be observed by an application due to 4 superfluous bytes being added to the pages data.
Fixes: 277e4ab7d530 ("SUNRPC: Simplify TCP receive code by switching to using iterators") Signed-off-by: Dan Aloni dan@kernelim.com Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sunrpc/xprtsock.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index c93ff70da3f98..c56a66cdf4ac8 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -433,7 +433,8 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr *msg, int flags, if (ret <= 0) goto sock_err; xs_flush_bvec(buf->bvec, ret, seek + buf->page_base); - offset += ret - buf->page_base; + ret -= buf->page_base; + offset += ret; if (offset == count || msg->msg_flags & (MSG_EOR|MSG_TRUNC)) goto out; if (ret != want)