From fae5c27e842fef2c59ea3ab4a9afaf903cbd267e Mon Sep 17 00:00:00 2001 From: Xufeng Zhang Date: Tue, 21 Jun 2011 10:43:40 +0000 Subject: [PATCH] udp/recvmsg: Clear MSG_TRUNC flag when starting over for a new packet [ Upstream commit 9cfaa8def1c795a512bc04f2aec333b03724ca2e ] 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 Signed-off-by: Paul Gortmaker Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/udp.c | 3 +++ net/ipv6/udp.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 659f3b2ea851..743a1210ac06 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1203,6 +1203,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; } diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index e363c6c76af9..3e9969b429b6 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -443,6 +443,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; } -- 2.39.5