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authorGao Feng <gfree.wind@vip.163.com>2018-05-30 10:29:31 +0800
committerPablo Neira Ayuso <pablo@netfilter.org>2018-06-01 10:14:51 +0200
commit8f4d19aacb64f2b3d65c8cf7974c3d153224b5f2 (patch)
treea8d0496a35d5eb92d8517017b8ccea917128fc8a /net
parent664088f8d68178809b848ca450f2797efb34e8e7 (diff)
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netfilter: xt_CT: Reject the non-null terminated string from user space
The helper and timeout strings are from user-space, we need to make sure they are null terminated. If not, evil user could make kernel read the unexpected memory, even print it when fail to find by the following codes. pr_info_ratelimited("No such helper \"%s\"\n", helper_name); Signed-off-by: Gao Feng <gfree.wind@vip.163.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/xt_CT.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index 8790190c6feb..03b9a50ec93b 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -245,12 +245,22 @@ static int xt_ct_tg_check(const struct xt_tgchk_param *par,
}
if (info->helper[0]) {
+ if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
+ ret = -ENAMETOOLONG;
+ goto err3;
+ }
+
ret = xt_ct_set_helper(ct, info->helper, par);
if (ret < 0)
goto err3;
}
if (info->timeout[0]) {
+ if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
+ ret = -ENAMETOOLONG;
+ goto err4;
+ }
+
ret = xt_ct_set_timeout(ct, par, info->timeout);
if (ret < 0)
goto err4;