From 4d7ccae75134a48e2e062f9f4f3587adb0df9496 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Tue, 12 Sep 2017 15:07:10 +0200 Subject: [PATCH] tools/xenstore: dont unlink connection object twice A connection object of a domain with associated stubdom has two parents: the domain and the stubdom. When cleaning up the list of active domains in domain_cleanup() make sure not to unlink the connection twice from the same domain. This could happen when the domain and its stubdom are being destroyed at the same time leading to the domain loop being entered twice. Additionally don't use talloc_free() in this case as it will remove a random parent link, leading eventually to a memory leak. Use talloc_unlink() instead specifying the context from which the connection object should be removed. This is CVE-2017-14317 / XSA-233. Reported-by: Eric Chanudet Signed-off-by: Juergen Gross Reviewed-by: Ian Jackson master commit: 562a1c0f7ef3fbf3c122c3dfa4f2ad9dd51da9fe master date: 2017-09-12 14:44:56 +0200 --- tools/xenstore/xenstored_domain.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c index 18ac327a2d..17a66be339 100644 --- a/tools/xenstore/xenstored_domain.c +++ b/tools/xenstore/xenstored_domain.c @@ -221,10 +221,11 @@ static int destroy_domain(void *_domain) static void domain_cleanup(void) { xc_dominfo_t dominfo; - struct domain *domain, *tmp; + struct domain *domain; int notify = 0; - list_for_each_entry_safe(domain, tmp, &domains, list) { + again: + list_for_each_entry(domain, &domains, list) { if (xc_domain_getinfo(*xc_handle, domain->domid, 1, &dominfo) == 1 && dominfo.domid == domain->domid) { @@ -236,8 +237,12 @@ static void domain_cleanup(void) if (!dominfo.dying) continue; } - talloc_free(domain->conn); - notify = 0; /* destroy_domain() fires the watch */ + if (domain->conn) { + talloc_unlink(talloc_autofree_context(), domain->conn); + domain->conn = NULL; + notify = 0; /* destroy_domain() fires the watch */ + goto again; + } } if (notify)