[AUDIT] : Increase skb->truesize in audit_expand
diff mbox series

Message ID 20080128111018.GA6442@gondor.apana.org.au
State New, archived
Headers show
Series
  • [AUDIT] : Increase skb->truesize in audit_expand
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Commit Message

Herbert Xu Jan. 28, 2008, 11:10 a.m. UTC
Hi:

[AUDIT]: Increase skb->truesize in audit_expand

The recent UDP patch exposed this bug in the audit code.  It
was calling pskb_expand_head without increasing skb->truesize.
The caller of pskb_expand_head needs to do so because that function
is designed to be called in places where truesize is already fixed
and therefore it doesn't update its value.

Because the audit system is using it in a place where the truesize
has not yet been fixed, it needs to update its value manually.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Cheers,

Comments

James Morris Jan. 28, 2008, 2:13 p.m. UTC | #1
On Mon, 28 Jan 2008, Herbert Xu wrote:

> Hi:
> 
> [AUDIT]: Increase skb->truesize in audit_expand
> 
> The recent UDP patch exposed this bug in the audit code.  It
> was calling pskb_expand_head without increasing skb->truesize.
> The caller of pskb_expand_head needs to do so because that function
> is designed to be called in places where truesize is already fixed
> and therefore it doesn't update its value.
> 
> Because the audit system is using it in a place where the truesize
> has not yet been fixed, it needs to update its value manually.
> 
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Acked-by: James Morris <jmorris@namei.org>


(Candidate for stable ?)


- James
David Miller Jan. 29, 2008, 4:47 a.m. UTC | #2
From: James Morris <jmorris@namei.org>
Date: Tue, 29 Jan 2008 01:13:03 +1100 (EST)

> On Mon, 28 Jan 2008, Herbert Xu wrote:
> 
> > Hi:
> > 
> > [AUDIT]: Increase skb->truesize in audit_expand
> > 
> > The recent UDP patch exposed this bug in the audit code.  It
> > was calling pskb_expand_head without increasing skb->truesize.
> > The caller of pskb_expand_head needs to do so because that function
> > is designed to be called in places where truesize is already fixed
> > and therefore it doesn't update its value.
> > 
> > Because the audit system is using it in a place where the truesize
> > has not yet been fixed, it needs to update its value manually.
> > 
> > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> 
> Acked-by: James Morris <jmorris@namei.org>
> 
> 
> (Candidate for stable ?)

Applied, and yes I'll queue this up for -stable.
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Patch
diff mbox series

diff --git a/kernel/audit.c b/kernel/audit.c
index f93c271..801c946 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1200,13 +1200,17 @@  struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 static inline int audit_expand(struct audit_buffer *ab, int extra)
 {
 	struct sk_buff *skb = ab->skb;
-	int ret = pskb_expand_head(skb, skb_headroom(skb), extra,
-				   ab->gfp_mask);
+	int oldtail = skb_tailroom(skb);
+	int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
+	int newtail = skb_tailroom(skb);
+
 	if (ret < 0) {
 		audit_log_lost("out of memory in audit_expand");
 		return 0;
 	}
-	return skb_tailroom(skb);
+
+	skb->truesize += newtail - oldtail;
+	return newtail;
 }
 
 /*