ipv6: fix calculation of option len in ip6_append_data
tot_len does specify the size of struct ipv6_txoptions. We need opt_flen +
opt_nflen to calculate the overall length of additional ipv6 extensions.
I found this while auditing the ipv6 output path for a memory corruption
reported by Alexey Preobrazhensky while he fuzzed an instrumented
AddressSanitizer kernel with trinity. This may or may not be the cause
of the original bug.
Fixes: 4df98e76cd
("ipv6: pmtudisc setting not respected with UFO/CORK")
Reported-by: Alexey Preobrazhensky <preobr@google.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -1229,7 +1229,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
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unsigned int maxnonfragsize, headersize;
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headersize = sizeof(struct ipv6hdr) +
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(opt ? opt->tot_len : 0) +
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(opt ? opt->opt_flen + opt->opt_nflen : 0) +
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(dst_allfrag(&rt->dst) ?
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sizeof(struct frag_hdr) : 0) +
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rt->rt6i_nfheader_len;
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