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[67.180.167.114]) by smtp.googlemail.com with ESMTPSA id n82sm13629702pfa.45.2018.01.24.17.16.10 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 24 Jan 2018 17:16:10 -0800 (PST) Message-ID: <1516842969.3715.41.camel@gmail.com> Subject: [PATCH v2 net] netfilter: x_tables: avoid out-of-bounds reads in xt_request_find_{match|target} From: Eric Dumazet To: Pablo Neira Ayuso , Florian Westphal Cc: netdev , netfilter-devel@vger.kernel.org Date: Wed, 24 Jan 2018 17:16:09 -0800 In-Reply-To: <20180125001336.ilboagwlcpck54ip@salvia> References: <1516834188.3715.35.camel@gmail.com> <20180124231952.GC14192@breakpoint.cc> <20180124235056.ahubcyqostttvtbx@salvia> <20180125001336.ilboagwlcpck54ip@salvia> X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet It looks like syzbot found its way into netfilter territory. Issue here is that @name comes from user space and might not be null terminated. Out-of-bound reads happen, KASAN is not happy. v2 added similar fix for xt_request_find_target(), as Florian advised. Signed-off-by: Eric Dumazet Reported-by: syzbot Acked-by: Florian Westphal --- No Fixes: tag, bug seems to be a day-0 one.  net/netfilter/x_tables.c |    6 ++++++  1 file changed, 6 insertions(+) diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index 55802e97f906d1987ed78b4296584deb38e5f876..ecffc51ce83b07c063a0db67cdb33d9bf48a75ac 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -210,6 +210,9 @@ xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision) { struct xt_match *match; + if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN) + return ERR_PTR(-EINVAL); + match = xt_find_match(nfproto, name, revision); if (IS_ERR(match)) { request_module("%st_%s", xt_prefix[nfproto], name); @@ -252,6 +255,9 @@ struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision) { struct xt_target *target; + if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN) + return ERR_PTR(-EINVAL); + target = xt_find_target(af, name, revision); if (IS_ERR(target)) { request_module("%st_%s", xt_prefix[af], name);