From 60769501a86b57c45d08eb130f925aeab31c9132 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 commit 9cfaa8def1c795a512bc04f2aec333b03724ca2e upstream. 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: Paul Gortmaker --- 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 ff6a18ea8151..7932dc68c669 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 a0a6a0849796..a1d3d32237dd 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