From 27bf90a14670283a899b96c56dd23f8413e0973e Mon Sep 17 00:00:00 2001 From: David Lamparter Date: Wed, 4 Jun 2014 00:59:01 +0200 Subject: [PATCH] bgpd: fix double free after extcommunity set (BZ#799) The route-map extcommunity set code was incorrectly assuming that it owns the intern'd struct ecommunity reference. In reality, the intern'd reference belongs to bgp_update_receive() and we're not supposed to touch it in the route-map code. Instead, like all the other set commands, we use a on-heap but non-intern'd ecommunity to set the new value. This is then either intern'd in bgp_update_main/_rsclient() through bgp_attr_intern(), or free'd through bgp_attr_flush(). This fixes Bugzilla #799, which is that bgpd otherwise crashes with a double free. The ecommunity got unintern'd first in the route-map set command, then in bgp_update_receive(). Debugged-by: Milan Kocian Reported-by: Florian S Signed-off-by: David Lamparter --- bgpd/bgp_routemap.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/bgpd/bgp_routemap.c b/bgpd/bgp_routemap.c index eb5e80f..36d177d 100644 --- a/bgpd/bgp_routemap.c +++ b/bgpd/bgp_routemap.c @@ -1552,14 +1552,19 @@ route_set_ecommunity (void *rule, struct prefix *prefix, old_ecom = (bgp_attr_extra_get (bgp_info->attr))->ecommunity; if (old_ecom) - new_ecom = ecommunity_merge (ecommunity_dup (old_ecom), ecom); + { + new_ecom = ecommunity_merge (ecommunity_dup (old_ecom), ecom); + + /* old_ecom->refcnt = 1 => owned elsewhere, e.g. bgp_update_receive() + * ->refcnt = 0 => set by a previous route-map statement */ + if (!old_ecom->refcnt) + ecommunity_free (&old_ecom); + } else new_ecom = ecommunity_dup (ecom); - bgp_info->attr->extra->ecommunity = ecommunity_intern (new_ecom); - - if (old_ecom) - ecommunity_unintern (&old_ecom); + /* will be intern()'d or attr_flush()'d by bgp_update_main() */ + bgp_info->attr->extra->ecommunity = new_ecom; bgp_info->attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES); } -- 2.0.1