diff options
Diffstat (limited to 'target/linux/generic/patches-4.1/080-ipv6-ip6_fragment-fix-headroom-tests-and-skb-leak.patch')
| -rw-r--r-- | target/linux/generic/patches-4.1/080-ipv6-ip6_fragment-fix-headroom-tests-and-skb-leak.patch | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/target/linux/generic/patches-4.1/080-ipv6-ip6_fragment-fix-headroom-tests-and-skb-leak.patch b/target/linux/generic/patches-4.1/080-ipv6-ip6_fragment-fix-headroom-tests-and-skb-leak.patch new file mode 100644 index 0000000..7de8987 --- /dev/null +++ b/target/linux/generic/patches-4.1/080-ipv6-ip6_fragment-fix-headroom-tests-and-skb-leak.patch @@ -0,0 +1,101 @@ +From: Florian Westphal <fw@strlen.de> +Date: Thu, 17 Sep 2015 11:24:48 +0100 +Subject: [PATCH] ipv6: ip6_fragment: fix headroom tests and skb leak + +David Woodhouse reports skb_under_panic when we try to push ethernet +header to fragmented ipv6 skbs: + + skbuff: skb_under_panic: text:c1277f1e len:1294 put:14 head:dec98000 + data:dec97ffc tail:0xdec9850a end:0xdec98f40 dev:br-lan +[..] +ip6_finish_output2+0x196/0x4da + +David further debugged this: + [..] offending fragments were arriving here with skb_headroom(skb)==10. + Which is reasonable, being the Solos ADSL card's header of 8 bytes + followed by 2 bytes of PPP frame type. + +The problem is that if netfilter ipv6 defragmentation is used, skb_cow() +in ip6_forward will only see reassembled skb. + +Therefore, headroom is overestimated by 8 bytes (we pulled fragment +header) and we don't check the skbs in the frag_list either. + +We can't do these checks in netfilter defrag since outdev isn't known yet. + +Furthermore, existing tests in ip6_fragment did not consider the fragment +or ipv6 header size when checking headroom of the fraglist skbs. + +While at it, also fix a skb leak on memory allocation -- ip6_fragment +must consume the skb. + +I tested this e1000 driver hacked to not allocate additional headroom +(we end up in slowpath, since LL_RESERVED_SPACE is 16). + +If 2 bytes of headroom are allocated, fastpath is taken (14 byte +ethernet header was pulled, so 16 byte headroom available in all +fragments). + +Reported-by: David Woodhouse <dwmw2@infradead.org> +Diagnosed-by: David Woodhouse <dwmw2@infradead.org> +Signed-off-by: Florian Westphal <fw@strlen.de> +Closes 20532 +--- + +--- a/net/ipv6/ip6_output.c ++++ b/net/ipv6/ip6_output.c +@@ -584,20 +584,22 @@ int ip6_fragment(struct sock *sk, struct + } + mtu -= hlen + sizeof(struct frag_hdr); + ++ hroom = LL_RESERVED_SPACE(rt->dst.dev); + if (skb_has_frag_list(skb)) { + int first_len = skb_pagelen(skb); + struct sk_buff *frag2; + + if (first_len - hlen > mtu || + ((first_len - hlen) & 7) || +- skb_cloned(skb)) ++ skb_cloned(skb) || ++ skb_headroom(skb) < (hroom + sizeof(struct frag_hdr))) + goto slow_path; + + skb_walk_frags(skb, frag) { + /* Correct geometry. */ + if (frag->len > mtu || + ((frag->len & 7) && frag->next) || +- skb_headroom(frag) < hlen) ++ skb_headroom(frag) < (hlen + hroom + sizeof(struct frag_hdr))) + goto slow_path_clean; + + /* Partially cloned skb? */ +@@ -614,8 +616,6 @@ int ip6_fragment(struct sock *sk, struct + + err = 0; + offset = 0; +- frag = skb_shinfo(skb)->frag_list; +- skb_frag_list_init(skb); + /* BUILD HEADER */ + + *prevhdr = NEXTHDR_FRAGMENT; +@@ -623,8 +623,11 @@ int ip6_fragment(struct sock *sk, struct + if (!tmp_hdr) { + IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), + IPSTATS_MIB_FRAGFAILS); +- return -ENOMEM; ++ err = -ENOMEM; ++ goto fail; + } ++ frag = skb_shinfo(skb)->frag_list; ++ skb_frag_list_init(skb); + + __skb_pull(skb, hlen); + fh = (struct frag_hdr *)__skb_push(skb, sizeof(struct frag_hdr)); +@@ -722,7 +725,6 @@ slow_path: + */ + + *prevhdr = NEXTHDR_FRAGMENT; +- hroom = LL_RESERVED_SPACE(rt->dst.dev); + troom = rt->dst.dev->needed_tailroom; + + /* |