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authorXufeng Zhang <xufeng.zhang@windriver.com>2011-06-21 10:43:39 +0000
committerDavid S. Miller <davem@davemloft.net>2011-06-21 22:34:27 -0700
commit32c90254ed4a0c698caa0794ebb4de63fcc69631 (patch)
tree4f0e4bb2cfe98c587792ba223ea3791102b43c1a
parent58fa45973117ab7a79d5b6818275a887867fc4d7 (diff)
ipv6/udp: Use the correct variable to determine non-blocking condition
udpv6_recvmsg() function is not using the correct variable to determine whether or not the socket is in non-blocking operation, this will lead to unexpected behavior when a UDP checksum error occurs. Consider a non-blocking udp receive scenario: when udpv6_recvmsg() is called by sock_common_recvmsg(), MSG_DONTWAIT bit of flags variable in udpv6_recvmsg() is cleared by "flags & ~MSG_DONTWAIT" in this call: err = sk->sk_prot->recvmsg(iocb, sk, msg, size, flags & MSG_DONTWAIT, flags & ~MSG_DONTWAIT, &addr_len); i.e. with udpv6_recvmsg() getting these values: int noblock = flags & MSG_DONTWAIT int flags = flags & ~MSG_DONTWAIT So, when udp checksum error occurs, the execution will go to csum_copy_err, and then the problem happens: csum_copy_err: ............... if (flags & MSG_DONTWAIT) return -EAGAIN; goto try_again; ............... But it will always go to try_again as MSG_DONTWAIT has been cleared from flags at call time -- only noblock contains the original value of MSG_DONTWAIT, so the test should be: if (noblock) return -EAGAIN; This is also consistent with what the ipv4/udp code does. 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>
-rw-r--r--net/ipv6/udp.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 41f8c9c08dba..1e7a43f500ab 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -453,7 +453,7 @@ csum_copy_err:
}
unlock_sock_fast(sk, slow);
- if (flags & MSG_DONTWAIT)
+ if (noblock)
return -EAGAIN;
goto try_again;
}