path: root/net/unix
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authorAnton Blanchard <anton@samba.org>2014-03-05 14:29:58 +1100
committerDavid S. Miller <davem@davemloft.net>2014-03-06 16:19:33 -0500
commit0a13404dd3bf4ea870e3d96270b5a382edca85c0 (patch)
tree89d909341dd6b885060ed2fcec4779392c3b8ff5 /net/unix
parentadca4767821e54c72d4a2f467af77923f2c87e07 (diff)
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')
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);

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