From: Steffen Klassert steffen.klassert@secunet.com
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@secunet.com Signed-off-by: Tadeusz Struk tadeusz.struk@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/esp.h | 2 ++ include/net/sock.h | 1 + net/ipv4/esp4.c | 5 +++++ net/ipv6/esp6.c | 5 +++++ 4 files changed, 13 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 @@ -2670,6 +2670,7 @@ extern int sysctl_optmem_max; extern __u32 sysctl_wmem_default; extern __u32 sysctl_rmem_default;
+#define SKB_FRAG_PAGE_ORDER get_order(32768) DECLARE_STATIC_KEY_FALSE(net_high_order_alloc_disable_key);
static inline int sk_get_wmem0(const struct sock *sk, const struct proto *proto) --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -448,6 +448,7 @@ 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 TCP/UDP Encapsulation */ if (x->encap) { @@ -457,6 +458,10 @@ 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 @@ -483,6 +483,7 @@ int esp6_output_head(struct xfrm_state * 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 * 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;