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From 4c39012783e0e376603138dddae9cd876bdd01ce Mon Sep 17 00:00:00 2001
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From: Thomas Haller <thaller@redhat.com>
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Date: Mon, 6 Feb 2017 22:23:52 +0100
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Subject: [PATCH 1/2] lib: check for integer-overflow in nlmsg_reserve()
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In general, libnl functions are not robust against calling with
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invalid arguments. Thus, never call libnl functions with invalid
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arguments. In case of nlmsg_reserve() this means never provide
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a @len argument that causes overflow.
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Still, add an additional safeguard to avoid exploiting such bugs.
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Assume that @pad is a trusted, small integer.
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Assume that n->nm_size is a valid number of allocated bytes (and thus
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much smaller then SIZE_T_MAX).
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Assume, that @len may be set to an untrusted value. Then the patch
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avoids an integer overflow resulting in reserving too few bytes.
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(cherry picked from commit 3e18948f17148e6a3c4255bdeaaf01ef6081ceeb)
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---
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lib/msg.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/lib/msg.c b/lib/msg.c
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index e8a7e99..f30fd2d 100644
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--- a/lib/msg.c
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+++ b/lib/msg.c
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@@ -410,6 +410,9 @@ void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
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size_t nlmsg_len = n->nm_nlh->nlmsg_len;
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size_t tlen;
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+ if (len > n->nm_size)
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+ return NULL;
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+
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tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;
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if ((tlen + nlmsg_len) > n->nm_size)
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--
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2.9.3
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From 1b347b7e5892eac5ea71090b8ec6c08756b0dcd4 Mon Sep 17 00:00:00 2001
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From: Thomas Haller <thaller@redhat.com>
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Date: Wed, 18 Jan 2017 11:59:23 +0100
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Subject: [PATCH 2/2] lib/attr.c: check for valid length argument in
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nla_reserve()
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https://github.com/thom311/libnl/issues/124
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(cherry picked from commit c473d59f972c35c5a7363d52ee6ee1e0792de0f8)
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---
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lib/attr.c | 11 +++++++++--
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1 file changed, 9 insertions(+), 2 deletions(-)
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diff --git a/lib/attr.c b/lib/attr.c
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index a3d1b16..0dca3ec 100644
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--- a/lib/attr.c
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+++ b/lib/attr.c
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@@ -457,7 +457,10 @@ struct nlattr *nla_reserve(struct nl_msg *msg, int attrtype, int attrlen)
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{
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struct nlattr *nla;
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int tlen;
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-
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+
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+ if (attrlen < 0)
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+ return NULL;
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+
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tlen = NLMSG_ALIGN(msg->nm_nlh->nlmsg_len) + nla_total_size(attrlen);
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if (tlen > msg->nm_size)
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@@ -499,8 +502,12 @@ int nla_put(struct nl_msg *msg, int attrtype, int datalen, const void *data)
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struct nlattr *nla;
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nla = nla_reserve(msg, attrtype, datalen);
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- if (!nla)
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+ if (!nla) {
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+ if (datalen < 0)
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+ return -NLE_INVAL;
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+
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return -NLE_NOMEM;
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+ }
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if (datalen > 0) {
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memcpy(nla_data(nla), data, datalen);
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--
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2.9.3
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