commit 890ae4fb1adfa13e37aaf5261e089e8c195a75cf Author: Nick Mathewson <nickm@torproject.org> Date: Wed Mar 3 15:14:31 2021 -0500 Fix detection of point to insert signatures on a pending consensus. We were looking for the first instance of "directory-signature " when instead the correct behavior is to look for the first instance of "directory-signature " at the start of a line. Unfortunately, this can be exploited as to crash authorities while they're voting. Fixes #40316; bugfix on 0.2.2.4-alpha. This is TROVE-2021-002, also tracked as CVE-2021-28090. --- changes/bug40316 | 5 +++++ src/feature/dirauth/dirvote.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/changes/bug40316 b/changes/bug40316 new file mode 100644 index 0000000000..cd275b5c9c --- /dev/null +++ b/changes/bug40316 @@ -0,0 +1,5 @@ + o Major bugfixes (security, denial of service): + - Fix a bug in appending detached signatures to a pending consensus + document that could be used to crash a directory authority. + Fixes bug 40316; bugfix on 0.2.2.6-alpha. Tracked as + TROVE-2021-002 and CVE-2021-28090. diff --git a/src/feature/dirauth/dirvote.c b/src/feature/dirauth/dirvote.c index af8b3dc207..9e01cee42a 100644 --- a/src/feature/dirauth/dirvote.c +++ b/src/feature/dirauth/dirvote.c @@ -3520,7 +3520,7 @@ dirvote_add_signatures_to_pending_consensus( strlen(pc->body) + strlen(new_signatures) + 1; pc->body = tor_realloc(pc->body, new_consensus_len); dst_end = pc->body + new_consensus_len; - dst = strstr(pc->body, "directory-signature "); + dst = (char *) find_str_at_start_of_line(pc->body, "directory-signature "); tor_assert(dst); strlcpy(dst, new_signatures, dst_end-dst);