From: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
[ Upstream commit ebe48d368e97d007bfeb76fcb065d6cfc4c96645 ]
The maximum message size that can be send is bigger than
the maximum site that skb_page_frag_refill can allocate.
So it is possible to write beyond the allocated buffer.
Fix this by doing a fallback to COW in that case.
v2:
Avoid get get_order() costs as suggested by Linus Torvalds.
Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
Reported-by: valis <sec@valis.email>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/net/esp.h | 2 ++
net/ipv4/esp4.c | 5 +++++
net/ipv6/esp6.c | 5 +++++
3 files changed, 12 insertions(+)
diff --git a/include/net/esp.h b/include/net/esp.h
index 9c5637d41d95..90cd02ff77ef 100644
--- a/include/net/esp.h
+++ b/include/net/esp.h
@@ -4,6 +4,8 @@
#include <linux/skbuff.h>
+#define ESP_SKB_FRAG_MAXSIZE (PAGE_SIZE << SKB_FRAG_PAGE_ORDER)
+
struct ip_esp_hdr;
static inline struct ip_esp_hdr *ip_esp_hdr(const struct sk_buff *skb)
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index e1b1d080e908..70e6c87fbe3d 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -446,6 +446,7 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
+ unsigned int allocsz;
/* this is non-NULL only with TCP/UDP Encapsulation */
if (x->encap) {
@@ -455,6 +456,10 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
return err;
}
+ allocsz = ALIGN(skb->data_len + tailen, L1_CACHE_BYTES);
+ if (allocsz > ESP_SKB_FRAG_MAXSIZE)
+ goto cow;
+
if (!skb_cloned(skb)) {
if (tailen <= skb_tailroom(skb)) {
nfrags = 1;
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 883b53fd7846..b7b573085bd5 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -483,6 +483,7 @@ int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
+ unsigned int allocsz;
if (x->encap) {
int err = esp6_output_encap(x, skb, esp);
@@ -491,6 +492,10 @@ int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info
return err;
}
+ allocsz = ALIGN(skb->data_len + tailen, L1_CACHE_BYTES);
+ if (allocsz > ESP_SKB_FRAG_MAXSIZE)
+ goto cow;
+
if (!skb_cloned(skb)) {
if (tailen <= skb_tailroom(skb)) {
nfrags = 1;
--
2.34.1
