[tor-commits] [tor/master] Do not look inside bogus microdesc when listing its digest as invalid

[asn at torproject.org]

commit e7d7e04155f0c7dd1282d4c77bdd02cae8bc0fe7
Author: Nick Mathewson <nickm at torproject.org>
Date:   Mon Sep 9 12:58:30 2019 -0400

    Do not look inside bogus microdesc when listing its digest as invalid
    
    We have code in microdescs_parse_from_string() to record the digests
    of microdescriptors that we could not parse.  But right now, that
    code looks at the md->digest field, which is a bit inelegant, and
    will stand in the way of sensible refactoring.
    
    Instead, use a local variable to hold the digest.
---
 src/feature/dirparse/microdesc_parse.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/feature/dirparse/microdesc_parse.c b/src/feature/dirparse/microdesc_parse.c
index 441c3bb83..e77166066 100644
--- a/src/feature/dirparse/microdesc_parse.c
+++ b/src/feature/dirparse/microdesc_parse.c
@@ -167,6 +167,7 @@ microdescs_parse_from_string(const char *s, const char *eos,
       start_of_next_microdesc = eos;
 
     md = tor_malloc_zero(sizeof(microdesc_t));
+    uint8_t md_digest[DIGEST256_LEN];
     {
       const char *cp = tor_memstr(s, start_of_next_microdesc-s,
                                   "onion-key");
@@ -183,6 +184,7 @@ microdescs_parse_from_string(const char *s, const char *eos,
         md->body = (char*)cp;
       md->off = cp - start;
       crypto_digest256(md->digest, md->body, md->bodylen, DIGEST_SHA256);
+      memcpy(md_digest, md->digest, DIGEST256_LEN);
       if (no_onion_key) {
         log_fn(LOG_PROTOCOL_WARN, LD_DIR, "Malformed or truncated descriptor");
         goto next;
@@ -279,7 +281,7 @@ microdescs_parse_from_string(const char *s, const char *eos,
   next:
     if (! okay && invalid_digests_out) {
       smartlist_add(invalid_digests_out,
-                    tor_memdup(md->digest, DIGEST256_LEN));
+                    tor_memdup(md_digest, DIGEST256_LEN));
     }
     microdesc_free(md);
     md = NULL;