Commit 150ae0e9 authored Jan 28, 2015 by karl beldan Committed by David S. Miller Jan 28, 2015

lib/checksum.c: fix carry in csum_tcpudp_nofold

The carry from the 64->32bits folding was dropped, e.g with:
saddr=0xFFFFFFFF daddr=0xFF0000FF len=0xFFFF proto=0 sum=1,
csum_tcpudp_nofold returned 0 instead of 1.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 59ccaaaa

lib/checksum.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -47,6 +47,15 @@ static inline unsigned short from32to16(unsigned int x)
		return x;
		}

		static inline u32 from64to32(u64 x)
		{
		/* add up 32-bit and 32-bit for 32+c bit */
		x = (x & 0xffffffff) + (x >> 32);
		/* add up carry.. */
		x = (x & 0xffffffff) + (x >> 32);
		return (u32)x;
		}

		static unsigned int do_csum(const unsigned char *buff, int len)
		{
		int odd;
		@@ -195,8 +204,7 @@ __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
		#else
		s += (proto + len) << 8;
		#endif
		s += (s >> 32);
		return (__force __wsum)s;
		return (__force __wsum)from64to32(s);
		}
		EXPORT_SYMBOL(csum_tcpudp_nofold);
		#endif