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author | 2014-03-05 14:29:58 +1100 | |
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committer | 2014-03-06 16:19:33 -0500 | |
commit | 0a13404dd3bf4ea870e3d96270b5a382edca85c0 (patch) | |
tree | 89d909341dd6b885060ed2fcec4779392c3b8ff5 /net/unix/af_unix.c | |
parent | net: Improve SO_TIMESTAMPING documentation and fix a minor code bug (diff) | |
download | linux-0a13404dd3bf4ea870e3d96270b5a382edca85c0.tar.gz linux-0a13404dd3bf4ea870e3d96270b5a382edca85c0.tar.bz2 linux-0a13404dd3bf4ea870e3d96270b5a382edca85c0.zip |
net: unix socket code abuses csum_partial
The unix socket code is using the result of csum_partial to
hash into a lookup table:
unix_hash_fold(csum_partial(sunaddr, len, 0));
csum_partial is only guaranteed to produce something that can be
folded into a checksum, as its prototype explains:
* returns a 32-bit number suitable for feeding into itself
* or csum_tcpudp_magic
The 32bit value should not be used directly.
Depending on the alignment, the ppc64 csum_partial will return
different 32bit partial checksums that will fold into the same
16bit checksum.
This difference causes the following testcase (courtesy of
Gustavo) to sometimes fail:
#include <sys/socket.h>
#include <stdio.h>
int main()
{
int fd = socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0);
int i = 1;
setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &i, 4);
struct sockaddr addr;
addr.sa_family = AF_LOCAL;
bind(fd, &addr, 2);
listen(fd, 128);
struct sockaddr_storage ss;
socklen_t sslen = (socklen_t)sizeof(ss);
getsockname(fd, (struct sockaddr*)&ss, &sslen);
fd = socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0);
if (connect(fd, (struct sockaddr*)&ss, sslen) == -1){
perror(NULL);
return 1;
}
printf("OK\n");
return 0;
}
As suggested by davem, fix this by using csum_fold to fold the
partial 32bit checksum into a 16bit checksum before using it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/unix/af_unix.c')
-rw-r--r-- | net/unix/af_unix.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 29fc8bee9702..ce6ec6c2f4de 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -163,9 +163,8 @@ static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb) static inline unsigned int unix_hash_fold(__wsum n) { - unsigned int hash = (__force unsigned int)n; + unsigned int hash = (__force unsigned int)csum_fold(n); - hash ^= hash>>16; hash ^= hash>>8; return hash&(UNIX_HASH_SIZE-1); } |