From b9037521c6ba333178c3f3197c39be360aba229c Mon Sep 17 00:00:00 2001 From: Nick Mathewson Date: Mon, 11 Mar 2013 12:29:28 -0400 Subject: Fix a framing bug when reading versions from a versions cell. Our ++ should have been += 2. This means that we'd accept version numbers even when they started at an odd position. This bug should be harmless in practice for so long as every version number we allow begins with a 0 byte, but if we ever have a version number starting with 1, 2, 3, or 4, there will be trouble here. Fix for bug 8059, reported pseudonymously. Bugfix on 0.2.0.10-alpha -- specifically, commit 6fcda529, where during development I increased the width of a version to 16 bits without changing the loop step. --- changes/bug8059 | 6 ++++++ src/or/channeltls.c | 2 +- 2 files changed, 7 insertions(+), 1 deletion(-) create mode 100644 changes/bug8059 diff --git a/changes/bug8059 b/changes/bug8059 new file mode 100644 index 0000000000..47273ed0ac --- /dev/null +++ b/changes/bug8059 @@ -0,0 +1,6 @@ + o Minor bugfixes (protocol conformance): + - Fix a misframing issue when reading the version numbers in a + VERSIONS cell. Previously we would recognize [00 01 00 02] as + 'version 1, version 2, and version 0x100', when it should have + only included versions 1 and 2. Fixes bug 8059; bugfix on + 0.2.0.10-alpha. Reported pseudonymously. diff --git a/src/or/channeltls.c b/src/or/channeltls.c index 1035a14127..60693daeb2 100644 --- a/src/or/channeltls.c +++ b/src/or/channeltls.c @@ -1208,7 +1208,7 @@ channel_tls_process_versions_cell(var_cell_t *cell, channel_tls_t *chan) tor_assert(chan->conn->handshake_state); end = cell->payload + cell->payload_len; - for (cp = cell->payload; cp+1 < end; ++cp) { + for (cp = cell->payload; cp+1 < end; cp += 2) { uint16_t v = ntohs(get_uint16(cp)); if (is_or_protocol_version_known(v) && v > highest_supported_version) highest_supported_version = v; -- cgit v1.2.3-54-g00ecf