Patchwork [iproute] ip-link: Fix use after free in nl_get_ll_addr_len()

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Submitter Phil Sutter
Date March 1, 2018, 9:35 a.m.
Message ID <20180301093512.21254-1-phil@nwl.cc>
Download mbox | patch
Permalink /patch/462359/
State New
Headers show

Comments

Phil Sutter - March 1, 2018, 9:35 a.m.
Immediately after freeing the buffer returned from rtnl_talk(), it is
accessed again via pointer in struct rtattr array. This leads to some
builds not allowing to set an interface's MAC address because the
expected length value is garbage.

Fixes: 86bf43c7c2fdc ("lib/libnetlink: update rtnl_talk to support malloc buff at run time")
Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 ip/iplink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Patch

diff --git a/ip/iplink.c b/ip/iplink.c
index 230f4c5377d9f..d401311bcad9f 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -276,8 +276,9 @@  static int nl_get_ll_addr_len(unsigned int dev_index)
 		return -1;
 	}
 
+	len = RTA_PAYLOAD(tb[IFLA_ADDRESS]);
 	free(answer);
-	return RTA_PAYLOAD(tb[IFLA_ADDRESS]);
+	return len;
 }
 
 static void iplink_parse_vf_vlan_info(int vf, int *argcp, char ***argvp,