arp: fix seq_file handling bug

Hi David,

Please pull from:

bk://kernel.bkbits.net/acme/net-2.5

Now there is just this outstanding changeset. Now I have
some time to devote to fixing /proc/net/tcp seq_file handling.

- Arnaldo

You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.

===================================================================

[email protected], 2002-11-30 13:30:49-02:00, [email protected]
o arp: fix seq_file handling bug

When midnigth commander viewer is invoked it first opens the file, read 4 bytes (probably looking for a magic number), reading only 4 bytes makes state->is_pneigh not to be set neither the lock is taken, because only the header is being produced (v = (void *)1), so when arp_seq_stop is called the lock is dropped without having being taken: b00m

Thanks to Serge Kuznetsov for reporting this to me. Other seq_file code may have this problem, but by using mc viewer in all of /proc/net I haven't been able to reproduce this problem with any other file.

 arp.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -Nru a/net/ipv4/arp.c b/net/ipv4/arp.c
@@ -1282,7 +1282,7 @@
 {
 	struct arp_iter_state* state = seq->private;
 
-	if (!state->is_pneigh)
+	if (!state->is_pneigh && v != (void *)1)
 		read_unlock_bh(&arp_tbl.lock);
 }
 

===================================================================

This BitKeeper patch contains the following changesets:
1.864
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end

From: Arnaldo Carvalho de Melo <[email protected]>
Date: Sat, 30 Nov 2002 13:36:00 -0200

Please pull from:

bk://kernel.bkbits.net/acme/net-2.5

Pulled, thanks.

Now there is just this outstanding changeset. Now I have
some time to devote to fixing /proc/net/tcp seq_file handling.

Please let me know once you have this fixed, as it is holding up my net merges :-)

Em Sun, Dec 01, 2002 at 11:41:28PM -0800, David S. Miller escreveu:

I'll do, I was quite busy with Real Life(tm), but I'm back trying to reproduce this one here at home, but failed to do so, I telnetted to another machine and the ESTABLISHED connection was correctly shown, so I'll be testing on a busier machine at the office, not on vmware.

- Arnaldo