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author | Xufeng Zhang <xufeng.zhang@windriver.com> | 2011-06-21 10:43:39 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2011-06-21 22:34:27 -0700 |
commit | 32c90254ed4a0c698caa0794ebb4de63fcc69631 (patch) | |
tree | 4f0e4bb2cfe98c587792ba223ea3791102b43c1a /net/ipv6 | |
parent | 58fa45973117ab7a79d5b6818275a887867fc4d7 (diff) | |
download | linux-32c90254ed4a0c698caa0794ebb4de63fcc69631.tar.bz2 |
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>
Diffstat (limited to 'net/ipv6')
-rw-r--r-- | net/ipv6/udp.c | 2 |
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; } |