Messages in this thread Patch in this message | | | Date | Thu, 07 Jul 2011 17:15:48 -0700 | From | Greg KH <> | Subject | [016/107] udp/recvmsg: Clear MSG_TRUNC flag when starting over for a new packet |
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2.6.39-stable review patch. If anyone has any objections, please let us know.
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From: Xufeng Zhang <xufeng.zhang@windriver.com>
[ 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 <xufeng.zhang@windriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- net/ipv4/udp.c | 3 +++ net/ipv6/udp.c | 3 +++ 2 files changed, 6 insertions(+)
--- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1241,6 +1241,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; } --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -455,6 +455,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; }
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