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esp: Fix possible buffer overflow in ESP transformation

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commit ebe48d368e 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: cac2661c53 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a ("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>
This commit is contained in:
Steffen Klassert 2022-03-07 13:11:39 +01:00 committed by Greg Kroah-Hartman
parent 5149b89520
commit 2c8abafd6c
5 changed files with 15 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
include/net/esp.h
View file

@ -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)

3
include/net/sock.h
View file

@ -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 */

3
net/core/sock.c
View file

@ -2193,9 +2193,6 @@ static void sk_leave_memory_pressure(struct sock *sk)
}
}
/* 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

5
net/ipv4/esp4.c
View file

@ -257,6 +257,7 @@ 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 UDP Encapsulation */
if (x->encap) {
@ -266,6 +267,10 @@ 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;

5
net/ipv6/esp6.c
View file

@ -223,6 +223,11 @@ 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;
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)) {