Re: IPv4: sysctl table check failed [was: mmotm 2010-10-07-14-08 uploaded]

Andrew Morton [off-list ref] writes:

On Fri, 08 Oct 2010 00:22:15 +0200
Eric Dumazet [off-list ref] wrote:

quoted

Le vendredi 08 octobre 2010 __ 00:06 +0200, Jiri Slaby a __crit :

quoted

On 10/07/2010 11:08 PM, akpm@linux-foundation.org wrote:

quoted

The mm-of-the-moment snapshot 2010-10-07-14-08 has been uploaded to

Hi, I got bunch of "sysctl table check failed" below. All seem to be
related to ipv4:

I would say, sysctl check is buggy :(

min/max are optional

[PATCH] sysctl: min/max bounds are optional

sysctl check complains when proc_doulongvec_minmax or
proc_doulongvec_ms_jiffies_minmax are used by a vector of longs (with
more than one element), with no min or max value specified.

This is unexpected, given we had a bug on this min/max handling :)

Reported-by: Jiri Slaby <redacted>
Signed-off-by: Eric Dumazet <redacted>
---
 kernel/sysctl_check.c |    9 ---------
 1 file changed, 9 deletions(-)

diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index 04cdcf7..10b90d8 100644
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c

@@ -143,15 +143,6 @@ int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table)
 				if (!table->maxlen)
 					set_fail(&fail, table, "No maxlen");
 			}
-			if ((table->proc_handler == proc_doulongvec_minmax) ||
-			    (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
-				if (table->maxlen > sizeof (unsigned long)) {
-					if (!table->extra1)
-						set_fail(&fail, table, "No min");
-					if (!table->extra2)
-						set_fail(&fail, table, "No max");
-				}
-			}
 #ifdef CONFIG_PROC_SYSCTL
 			if (table->procname && !table->proc_handler)
 				set_fail(&fail, table, "No proc_handler");

That will probably fix it ;)

net-avoid-limits-overflow.patch is dependent on this patch.  Unless
Eric B squeaks I'll plan on sending this patch in for 2.6.37.

Oh.  I see. I actually had a sanity check for the case that was failing.
I probably spotted the buggy code and wanted to see if there was
anything that cared.

So sysctl_check was perfectly correct until the bug was removed from
proc_doulongvec_minmax.  Which also means we have been auditing the
kernel for quite a while to make certain that it is safe not to
increment min and max.

Eric