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: Vaibhav Rustagi vaibhavrustagi@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/esp.h | 2 ++ include/net/sock.h | 3 +++ net/core/sock.c | 3 --- net/ipv4/esp4.c | 5 +++++ net/ipv6/esp6.c | 5 +++++ 5 files changed, 15 insertions(+), 3 deletions(-)
--- 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 +2438,7 @@ extern int sysctl_optmem_max; extern __u32 sysctl_wmem_default; extern __u32 sysctl_rmem_default;
+/* On 32bit arches, an skb frag is limited to 2^15 */ +#define SKB_FRAG_PAGE_ORDER get_order(32768) + #endif /* _SOCK_H */ --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2193,9 +2193,6 @@ static void sk_leave_memory_pressure(str } }
-/* On 32bit arches, an skb frag is limited to 2^15 */ -#define SKB_FRAG_PAGE_ORDER get_order(32768) - /** * skb_page_frag_refill - check that a page_frag contains enough room * @sz: minimum size of the fragment we want to get --- 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 +223,11 @@ int esp6_output_head(struct xfrm_state * struct page *page; struct sk_buff *trailer; int tailen = esp->tailen; + unsigned int allocsz; + + 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)) {