100 lines
3.0 KiB
Diff
100 lines
3.0 KiB
Diff
From e69b535f92eafb599329bf725d9b4c6fd5d7fded Mon Sep 17 00:00:00 2001
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From: Paul Jakma <paul@jakma.org>
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Date: Sat, 6 Jan 2018 19:52:10 +0000
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Subject: bgpd/security: Fix double free of unknown attribute
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Security issue: Quagga-2018-1114
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See: https://www.quagga.net/security/Quagga-2018-1114.txt
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It is possible for bgpd to double-free an unknown attribute. This can happen
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via bgp_update_receive receiving an UPDATE with an invalid unknown attribute.
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bgp_update_receive then will call bgp_attr_unintern_sub and bgp_attr_flush,
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and the latter may try free an already freed unknown attr.
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* bgpd/bgp_attr.c: (transit_unintern) Take a pointer to the caller's storage
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for the (struct transit *), so that transit_unintern can NULL out the
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caller's reference if the (struct transit) is freed.
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(cluster_unintern) By inspection, appears to have a similar issue.
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(bgp_attr_unintern_sub) adjust for above.
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--- a/bgpd/bgp_attr.c
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+++ b/bgpd/bgp_attr.c
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@@ -186,15 +186,17 @@ cluster_intern (struct cluster_list *clu
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}
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void
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-cluster_unintern (struct cluster_list *cluster)
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+cluster_unintern (struct cluster_list **cluster)
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{
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- if (cluster->refcnt)
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- cluster->refcnt--;
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+ struct cluster_list *c = *cluster;
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+ if (c->refcnt)
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+ c->refcnt--;
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- if (cluster->refcnt == 0)
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+ if (c->refcnt == 0)
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{
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- hash_release (cluster_hash, cluster);
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- cluster_free (cluster);
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+ hash_release (cluster_hash, c);
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+ cluster_free (c);
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+ *cluster = NULL;
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}
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}
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@@ -344,15 +346,18 @@ transit_intern (struct transit *transit)
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}
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void
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-transit_unintern (struct transit *transit)
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+transit_unintern (struct transit **transit)
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{
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- if (transit->refcnt)
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- transit->refcnt--;
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+ struct transit *t = *transit;
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+
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+ if (t->refcnt)
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+ t->refcnt--;
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- if (transit->refcnt == 0)
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+ if (t->refcnt == 0)
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{
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- hash_release (transit_hash, transit);
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- transit_free (transit);
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+ hash_release (transit_hash, t);
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+ transit_free (t);
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+ *transit = NULL;
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}
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}
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@@ -793,11 +798,11 @@ bgp_attr_unintern_sub (struct attr *attr
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UNSET_FLAG(attr->flag, ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES));
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if (attr->extra->cluster)
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- cluster_unintern (attr->extra->cluster);
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+ cluster_unintern (&attr->extra->cluster);
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UNSET_FLAG(attr->flag, ATTR_FLAG_BIT (BGP_ATTR_CLUSTER_LIST));
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if (attr->extra->transit)
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- transit_unintern (attr->extra->transit);
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+ transit_unintern (&attr->extra->transit);
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}
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}
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--- a/bgpd/bgp_attr.h
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+++ b/bgpd/bgp_attr.h
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@@ -184,10 +184,10 @@ extern unsigned long int attr_unknown_co
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/* Cluster list prototypes. */
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extern int cluster_loop_check (struct cluster_list *, struct in_addr);
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-extern void cluster_unintern (struct cluster_list *);
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+extern void cluster_unintern (struct cluster_list **);
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/* Transit attribute prototypes. */
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-void transit_unintern (struct transit *);
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+void transit_unintern (struct transit **);
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/* Below exported for unit-test purposes only */
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struct bgp_attr_parser_args {
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