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author | Eric Dumazet <edumazet@google.com> | 2017-04-03 10:55:11 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-07-05 14:37:15 +0200 |
commit | 234e649840d191379cd132d89f4b01a2495cfcc3 (patch) | |
tree | 8138ed70bfe1e7c094763d3c9690055afc8531f7 /net/netfilter | |
parent | 095a41128cb6df913e24f95e43c57f378b5088bc (diff) | |
download | linux-stable-234e649840d191379cd132d89f4b01a2495cfcc3.tar.gz linux-stable-234e649840d191379cd132d89f4b01a2495cfcc3.tar.bz2 linux-stable-234e649840d191379cd132d89f4b01a2495cfcc3.zip |
netfilter: xt_TCPMSS: add more sanity tests on tcph->doff
commit 2638fd0f92d4397884fd991d8f4925cb3f081901 upstream.
Denys provided an awesome KASAN report pointing to an use
after free in xt_TCPMSS
I have provided three patches to fix this issue, either in xt_TCPMSS or
in xt_tcpudp.c. It seems xt_TCPMSS patch has the smallest possible
impact.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Denys Fedoryshchenko <nuclearcat@nuclearcat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/netfilter')
-rw-r--r-- | net/netfilter/xt_TCPMSS.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c index b7c43def0dc6..00f798b20b20 100644 --- a/net/netfilter/xt_TCPMSS.c +++ b/net/netfilter/xt_TCPMSS.c @@ -104,7 +104,7 @@ tcpmss_mangle_packet(struct sk_buff *skb, tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); tcp_hdrlen = tcph->doff * 4; - if (len < tcp_hdrlen) + if (len < tcp_hdrlen || tcp_hdrlen < sizeof(struct tcphdr)) return -1; if (info->mss == XT_TCPMSS_CLAMP_PMTU) { @@ -156,6 +156,10 @@ tcpmss_mangle_packet(struct sk_buff *skb, if (len > tcp_hdrlen) return 0; + /* tcph->doff has 4 bits, do not wrap it to 0 */ + if (tcp_hdrlen >= 15 * 4) + return 0; + /* * MSS Option not found ?! add it.. */ |