diff mbox series

[5.10] esp: Fix possible buffer overflow in ESP transformation

Message ID 20220317164159.1916929-1-tadeusz.struk@linaro.org
State New
Headers show
Series [5.10] esp: Fix possible buffer overflow in ESP transformation | expand

Commit Message

Tadeusz Struk March 17, 2022, 4:41 p.m. UTC 
From: Steffen Klassert <steffen.klassert@secunet.com>

Plese apply this on 5.10.y stable as well as it fixes the following
syzbot issues:

LINK: https://syzkaller.appspot.com/bug?id=517fa734b92b7db404c409b924cf5c997640e324
LINK: https://syzkaller.appspot.com/bug?id=57375340ab81a369df5da5eb16cfcd4aef9dfb9d

Here is a working patch.
---8<---

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.

Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
Reported-by: valis <sec@valis.email>
Reported-by: <syzbot+93ab2623dcb5c73eda9f@syzkaller.appspotmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.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(+)
diff mbox series

Patch

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/include/net/sock.h b/include/net/sock.h
index d50823df426c..865e0ff20a81 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2688,6 +2688,7 @@  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)
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 61dfb64e7256..b23b2bedca7a 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -448,6 +448,7 @@  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) {
@@ -457,6 +458,10 @@  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 cb708fbb1c17..ffcc30484c8d 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;