From 3cc0e873986fe594d0e96d07259b11f755325cb2 Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 9 Jun 2006 16:13:38 -0700
Subject: [PATCH] [NET]: Warn in __skb_trim if skb is paged
It's better to warn and fail rather than rarely triggering BUG on paths
that incorrectly call skb_trim/__skb_trim on a non-linear skb.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/skbuff.h | 24 ++++++++++++------------
net/core/skbuff.c | 7 ++-----
2 files changed, 14 insertions(+), 17 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 830f58fa03a2..93e4db221585 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -975,15 +975,16 @@ static inline void skb_reserve(struct sk_buff *skb, int len)
#define NET_SKB_PAD 16
#endif
-extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
+extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);
static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
{
- if (!skb->data_len) {
- skb->len = len;
- skb->tail = skb->data + len;
- } else
- ___pskb_trim(skb, len, 0);
+ if (unlikely(skb->data_len)) {
+ WARN_ON(1);
+ return;
+ }
+ skb->len = len;
+ skb->tail = skb->data + len;
}
/**
@@ -993,6 +994,7 @@ static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
*
* Cut the length of a buffer down by removing data from the tail. If
* the buffer is already under the length specified it is not modified.
+ * The skb must be linear.
*/
static inline void skb_trim(struct sk_buff *skb, unsigned int len)
{
@@ -1003,12 +1005,10 @@ static inline void skb_trim(struct sk_buff *skb, unsigned int len)
static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
{
- if (!skb->data_len) {
- skb->len = len;
- skb->tail = skb->data+len;
- return 0;
- }
- return ___pskb_trim(skb, len, 1);
+ if (skb->data_len)
+ return ___pskb_trim(skb, len);
+ __skb_trim(skb, len);
+ return 0;
}
static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 96cdcbe24ba2..bb7210f4005e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -801,12 +801,10 @@ struct sk_buff *skb_pad(struct sk_buff *skb, int pad)
return nskb;
}
-/* Trims skb to length len. It can change skb pointers, if "realloc" is 1.
- * If realloc==0 and trimming is impossible without change of data,
- * it is BUG().
+/* Trims skb to length len. It can change skb pointers.
*/
-int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc)
+int ___pskb_trim(struct sk_buff *skb, unsigned int len)
{
int offset = skb_headlen(skb);
int nfrags = skb_shinfo(skb)->nr_frags;
@@ -816,7 +814,6 @@ int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc)
int end = offset + skb_shinfo(skb)->frags[i].size;
if (end > len) {
if (skb_cloned(skb)) {
- BUG_ON(!realloc);
if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
return -ENOMEM;
}
--
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