This is a note to let you know that I've just added the patch titled
net: unix socket code abuses csum_partial
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-unix-socket-code-abuses-csum_partial.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 0a13404dd3bf4ea870e3d96270b5a382edca85c0 Mon Sep 17 00:00:00 2001
From: Anton Blanchard <anton@xxxxxxxxx>
Date: Wed, 5 Mar 2014 14:29:58 +1100
Subject: net: unix socket code abuses csum_partial
From: Anton Blanchard <anton@xxxxxxxxx>
commit 0a13404dd3bf4ea870e3d96270b5a382edca85c0 upstream.
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@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/unix/af_unix.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -160,9 +160,8 @@ static inline void unix_set_secdata(stru
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);
}
Patches currently in stable-queue which might be from anton@xxxxxxxxx are
queue-3.10/net-unix-socket-code-abuses-csum_partial.patch
queue-3.10/powerpc-align-p_dyn-p_rela-and-p_st-symbols.patch
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