From: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
commit ebe48d368e97d007bfeb76fcb065d6cfc4c96645 upstream.
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: Tadeusz Struk <tadeusz.struk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/esp.h | 2 ++
include/net/sock.h | 2 ++
net/ipv4/esp4.c | 5 +++++
net/ipv6/esp6.c | 5 +++++
4 files changed, 14 insertions(+)
--- 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)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2438,4 +2438,6 @@ extern int sysctl_optmem_max;
extern __u32 sysctl_wmem_default;
extern __u32 sysctl_rmem_default;
+#define SKB_FRAG_PAGE_ORDER get_order(32768)
+
#endif /* _SOCK_H */
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -257,6 +257,7 @@ int esp_output_head(struct xfrm_state *x
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
+ unsigned int allocsz;
/* this is non-NULL only with UDP Encapsulation */
if (x->encap) {
@@ -266,6 +267,10 @@ int esp_output_head(struct xfrm_state *x
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;
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -223,6 +223,7 @@ int esp6_output_head(struct xfrm_state *
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
+ unsigned int allocsz;
if (!skb_cloned(skb)) {
if (tailen <= skb_tailroom(skb)) {
@@ -611,6 +612,10 @@ static int esp6_input(struct xfrm_state
assoclen += seqhilen;
}
+ allocsz = ALIGN(skb->data_len + tailen, L1_CACHE_BYTES);
+ if (allocsz > ESP_SKB_FRAG_MAXSIZE)
+ goto cow;
+
if (!skb_cloned(skb)) {
if (!skb_is_nonlinear(skb)) {
nfrags = 1;
Patches currently in stable-queue which might be from steffen.klassert@xxxxxxxxxxx are
queue-4.14/esp-fix-possible-buffer-overflow-in-esp-transformation.patch
queue-4.14/xfrm-fix-xfrm-migrate-issues-when-address-family-cha.patch
