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-rw-r--r--changes/bug21278_prevention4
-rw-r--r--src/or/dirserv.c10
2 files changed, 14 insertions, 0 deletions
diff --git a/changes/bug21278_prevention b/changes/bug21278_prevention
new file mode 100644
index 0000000000..e07f0a670c
--- /dev/null
+++ b/changes/bug21278_prevention
@@ -0,0 +1,4 @@
+ o Minor features (directory authority):
+ - Directory authorities now reject descriptors that claim to be
+ malformed versions of Tor. Helps prevent exploitation of bug 21278.
+
diff --git a/src/or/dirserv.c b/src/or/dirserv.c
index 1b614b949e..fa3938b5ec 100644
--- a/src/or/dirserv.c
+++ b/src/or/dirserv.c
@@ -365,6 +365,16 @@ dirserv_get_status_impl(const char *id_digest, const char *nickname,
strmap_size(fingerprint_list->fp_by_name),
digestmap_size(fingerprint_list->status_by_digest));
+ if (platform) {
+ tor_version_t ver_tmp;
+ if (tor_version_parse_platform(platform, &ver_tmp, 1) < 0) {
+ if (msg) {
+ *msg = "Malformed platform string.";
+ }
+ return FP_REJECT;
+ }
+ }
+
/* Versions before Tor 0.2.4.18-rc are too old to support, and are
* missing some important security fixes too. Disable them. */
if (platform && !tor_version_as_new_as(platform,"0.2.4.18-rc")) {