From 5bd8baab087dff657e05387aee802e70304cc813 Mon Sep 17 00:00:00 2001 From: Sabrina Dubroca Date: Wed, 13 Apr 2022 10:10:50 +0200 Subject: esp: limit skb_page_frag_refill use to a single page Commit ebe48d368e97 ("esp: Fix possible buffer overflow in ESP transformation") tried to fix skb_page_frag_refill usage in ESP by capping allocsize to 32k, but that doesn't completely solve the issue, as skb_page_frag_refill may return a single page. If that happens, we will write out of bounds, despite the check introduced in the previous patch. This patch forces COW in cases where we would end up calling skb_page_frag_refill with a size larger than a page (first in esp_output_head with tailen, then in esp_output_tail with skb->data_len). Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible") Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible") Signed-off-by: Sabrina Dubroca Signed-off-by: Steffen Klassert --- net/ipv4/esp4.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'net/ipv4/esp4.c') diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index 70e6c87fbe3d..d747166bb291 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -446,7 +446,6 @@ 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) { @@ -456,8 +455,8 @@ 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) + if (ALIGN(tailen, L1_CACHE_BYTES) > PAGE_SIZE || + ALIGN(skb->data_len, L1_CACHE_BYTES) > PAGE_SIZE) goto cow; if (!skb_cloned(skb)) { -- cgit v1.2.3