5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
[ Upstream commit 13244cccc2b61ec715f0ac583d3037497004d4a5 ]
Like skb_pull but returns the original data pointer before pulling the
data after performing a check against sbk->len.
This allows to change code that does "struct foo *p = (void *)skb->data;"
which is hard to audit and error prone, to:
p = skb_pull_data(skb, sizeof(*p));
if (!p)
return;
Which is both safer and cleaner.
Acked-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Stable-dep-of: cda0d6a198e2 ("Bluetooth: qca: fix info leak when fetching fw build id")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/linux/skbuff.h | 2 ++
net/core/skbuff.c | 24 ++++++++++++++++++++++++
2 files changed, 26 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 15de91c65a09a..b230c422dc3b9 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2447,6 +2447,8 @@ static inline void *skb_pull_inline(struct sk_buff *skb, unsigned int len)
return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
}
+void *skb_pull_data(struct sk_buff *skb, size_t len);
+
void *__pskb_pull_tail(struct sk_buff *skb, int delta);
static inline void *__pskb_pull(struct sk_buff *skb, unsigned int len)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4ec8cfd357eba..17073429cc365 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2071,6 +2071,30 @@ void *skb_pull(struct sk_buff *skb, unsigned int len)
}
EXPORT_SYMBOL(skb_pull);
+/**
+ * skb_pull_data - remove data from the start of a buffer returning its
+ * original position.
+ * @skb: buffer to use
+ * @len: amount of data to remove
+ *
+ * This function removes data from the start of a buffer, returning
+ * the memory to the headroom. A pointer to the original data in the buffer
+ * is returned after checking if there is enough data to pull. Once the
+ * data has been pulled future pushes will overwrite the old data.
+ */
+void *skb_pull_data(struct sk_buff *skb, size_t len)
+{
+ void *data = skb->data;
+
+ if (skb->len < len)
+ return NULL;
+
+ skb_pull(skb, len);
+
+ return data;
+}
+EXPORT_SYMBOL(skb_pull_data);
+
/**
* skb_trim - remove end from a buffer
* @skb: buffer to alter
--
2.43.0
