Re: KASAN, xt_TCPMSS finally found nasty use-after-free bug? 4.10.8
From: Florian Westphal
Date: Sun Apr 02 2017 - 07:46:45 EST
Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> - for (i = sizeof(struct tcphdr); i <= tcp_hdrlen - TCPOLEN_MSS; i += optlen(opt, i)) {
> + for (i = sizeof(struct tcphdr); i < tcp_hdrlen - TCPOLEN_MSS; i += optlen(opt, i)) {
> if (opt[i] == TCPOPT_MSS && opt[i+1] == TCPOLEN_MSS) {
> u_int16_t oldmss;
maybe I am low on caffeeine but this looks fine, for tcp header with
only tcpmss this boils down to "20 <= 24 - 4" so we acccess offsets 20-23 which seems ok.