[patch 1/1] net/ipv4/netfilter/nf_nat_snmp_basic.c: correct the size argument to kzalloc

[patch 1/1] net/ipv4/netfilter/nf_nat_snmp_basic.c: correct the size argument to kzalloc

[akpm]

From: Julia Lawall <julia@diku.dk>

obj has type struct snmp_object **, not struct snmp_object *.  But indeed
it is not even clear why kmalloc is needed.  The memory is freed by the
end of the function, so the local variable of pointer type should be
sufficient.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@disable sizeof_type_expr@
type T;
T **x;
@@

  x =
  <+...sizeof(
- T
+ *x
  )...+>
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 net/ipv4/netfilter/nf_nat_snmp_basic.c |   31 ++++++++---------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff -puN net/ipv4/netfilter/nf_nat_snmp_basic.c~net-ipv4-correct-the-size-argument-to-kzalloc net/ipv4/netfilter/nf_nat_snmp_basic.c
--- a/net/ipv4/netfilter/nf_nat_snmp_basic.c~net-ipv4-correct-the-size-argument-to-kzalloc
+++ a/net/ipv4/netfilter/nf_nat_snmp_basic.c
@@ -1038,7 +1038,7 @@ static int snmp_parse_mangle(unsigned ch
 	unsigned int cls, con, tag, vers, pdutype;
 	struct asn1_ctx ctx;
 	struct asn1_octstr comm;
-	struct snmp_object **obj;
+	struct snmp_object *obj;
 
 	if (debug > 1)
 		hex_dump(msg, len);
@@ -1148,43 +1148,34 @@ static int snmp_parse_mangle(unsigned ch
 	if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
 		return 0;
 
-	obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC);
-	if (obj == NULL) {
-		if (net_ratelimit())
-			printk(KERN_WARNING "OOM in bsalg(%d)\n", __LINE__);
-		return 0;
-	}
-
 	while (!asn1_eoc_decode(&ctx, eoc)) {
 		unsigned int i;
 
-		if (!snmp_object_decode(&ctx, obj)) {
-			if (*obj) {
-				kfree((*obj)->id);
-				kfree(*obj);
+		if (!snmp_object_decode(&ctx, &obj)) {
+			if (obj) {
+				kfree(obj->id);
+				kfree(obj);
 			}
-			kfree(obj);
 			return 0;
 		}
 
 		if (debug > 1) {
 			printk(KERN_DEBUG "bsalg: object: ");
-			for (i = 0; i < (*obj)->id_len; i++) {
+			for (i = 0; i < obj->id_len; i++) {
 				if (i > 0)
 					printk(".");
-				printk("%lu", (*obj)->id[i]);
+				printk("%lu", obj->id[i]);
 			}
-			printk(": type=%u\n", (*obj)->type);
+			printk(": type=%u\n", obj->type);
 
 		}
 
-		if ((*obj)->type == SNMP_IPADDR)
+		if (obj->type == SNMP_IPADDR)
 			mangle_address(ctx.begin, ctx.pointer - 4 , map, check);
 
-		kfree((*obj)->id);
-		kfree(*obj);
+		kfree(obj->id);
+		kfree(obj);
 	}
-	kfree(obj);
 
 	if (!asn1_eoc_decode(&ctx, eoc))
 		return 0;
_

Re: [patch 1/1] net/ipv4/netfilter/nf_nat_snmp_basic.c: correct the size argument to kzalloc

[Patrick McHardy]

akpm@linux-foundation.org wrote:
> From: Julia Lawall <julia@diku.dk>
> 
> obj has type struct snmp_object **, not struct snmp_object *.  But indeed
> it is not even clear why kmalloc is needed.  The memory is freed by the
> end of the function, so the local variable of pointer type should be
> sufficient.

This one is already queued in nf-next-2.6.git.

Re: [patch 1/1] net/ipv4/netfilter/nf_nat_snmp_basic.c: correct the size argument to kzalloc

[Andrew Morton]

On Wed, 03 Feb 2010 01:37:20 +0100
Patrick McHardy <kaber@trash.net> wrote:

> akpm@linux-foundation.org wrote:
> > From: Julia Lawall <julia@diku.dk>
> > 
> > obj has type struct snmp_object **, not struct snmp_object *.  But indeed
> > it is not even clear why kmalloc is needed.  The memory is freed by the
> > end of the function, so the local variable of pointer type should be
> > sufficient.
> 
> This one is already queued in nf-next-2.6.git.

Recently?  It wasn't in today's linux-next.

Re: [patch 1/1] net/ipv4/netfilter/nf_nat_snmp_basic.c: correct the size argument to kzalloc

[Patrick McHardy]

Andrew Morton wrote:
> On Wed, 03 Feb 2010 01:37:20 +0100
> Patrick McHardy <kaber@trash.net> wrote:
> 
>> akpm@linux-foundation.org wrote:
>>> From: Julia Lawall <julia@diku.dk>
>>>
>>> obj has type struct snmp_object **, not struct snmp_object *.  But indeed
>>> it is not even clear why kmalloc is needed.  The memory is freed by the
>>> end of the function, so the local variable of pointer type should be
>>> sufficient.
>> This one is already queued in nf-next-2.6.git.
> 
> Recently?  It wasn't in today's linux-next.
> 

Actually I haven't merged it to Dave yet, but I will do so soon.
Its queued and safe however :)