Commit 9cfaa8de authored Jun 21, 2011 by Xufeng Zhang Committed by David S. Miller Jun 21, 2011

udp/recvmsg: Clear MSG_TRUNC flag when starting over for a new packet

Consider this scenario: When the size of the first received udp packet
is bigger than the receive buffer, MSG_TRUNC bit is set in msg->msg_flags.
However, if checksum error happens and this is a blocking socket, it will
goto try_again loop to receive the next packet. But if the size of the
next udp packet is smaller than receive buffer, MSG_TRUNC flag should not
be set, but because MSG_TRUNC bit is not cleared in msg->msg_flags before
receive the next packet, MSG_TRUNC is still set, which is wrong.

Fix this problem by clearing MSG_TRUNC flag when starting over for a
new packet.

Signed-off-by: Xufeng Zhang <xufeng.zhang@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 32c90254

net/ipv4/udp.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1249,6 +1249,9 @@ int udp_recvmsg(struct kiocb iocb, struct sock sk, struct msghdr *msg,

	if (noblock)		if (noblock)
	return -EAGAIN;		return -EAGAIN;

			/* starting over for a new packet */
			msg->msg_flags &= ~MSG_TRUNC;
	goto try_again;		goto try_again;
	}		}

net/ipv6/udp.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -455,6 +455,9 @@ int udpv6_recvmsg(struct kiocb iocb, struct sock sk,

	if (noblock)		if (noblock)
	return -EAGAIN;		return -EAGAIN;

			/* starting over for a new packet */
			msg->msg_flags &= ~MSG_TRUNC;
	goto try_again;		goto try_again;
	}		}