netmem: fix skb_frag_address_safe with unreadable skbs

skb_frag_address_safe() needs a check that the
skb_frag_page exists check similar to skb_frag_address().

Cc: ap420073@gmail.com
Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250619175239.3039329-1-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 9508968..4f6dcb3 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3665,7 +3665,13 @@ static inline void *skb_frag_address(const skb_frag_t *frag)
  */
 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
 {
-       void *ptr = page_address(skb_frag_page(frag));
+       struct page *page = skb_frag_page(frag);
+       void *ptr;
+
+       if (!page)
+               return NULL;
+
+       ptr = page_address(page);
        if (unlikely(!ptr))
                return NULL;