commit 80e3dc47272c9ba423d40ce367fb99d39c3150ec Author: Nick Mathewson nickm@torproject.org Date: Wed Feb 12 14:17:19 2020 -0500

Use more memory poisoning and better asserts around ewma code

Attempt to diagnose 32464; fixes 33290. --- changes/ticket33290 | 4 ++++ src/core/or/circuitmux.c | 8 ++++++-- src/core/or/circuitmux_ewma.c | 11 ++++++++--- 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/changes/ticket33290 b/changes/ticket33290 new file mode 100644 index 000000000..882764020 --- /dev/null +++ b/changes/ticket33290 @@ -0,0 +1,4 @@ + o Minor features (diagnostic): + - Improve assertions and add some memory-poisoning code to try to track + down possible causes of a rare crash (32564) in the EWMA code. + Closes ticket 33290. diff --git a/src/core/or/circuitmux.c b/src/core/or/circuitmux.c index b2628bec3..72f6ba662 100644 --- a/src/core/or/circuitmux.c +++ b/src/core/or/circuitmux.c @@ -79,6 +79,8 @@ #include "core/or/destroy_cell_queue_st.h" #include "core/or/or_circuit_st.h"

+#include "lib/crypt_ops/crypto_util.h" + /* * Private typedefs for circuitmux.c */ @@ -973,7 +975,10 @@ circuitmux_detach_circuit,(circuitmux_t *cmux, circuit_t *circ)) /* Now remove it from the map */ HT_REMOVE(chanid_circid_muxinfo_map, cmux->chanid_circid_map, hashent);

- /* Free the hash entry */ + /* Wipe and free the hash entry */ + // This isn't sensitive, but we want to be sure to know if we're accessing + // this accidentally. + memwipe(hashent, 0xef, sizeof(hashent)); tor_free(hashent); } } @@ -1334,4 +1339,3 @@ circuitmux_compare_muxes, (circuitmux_t *cmux_1, circuitmux_t *cmux_2)) return 0; } } - diff --git a/src/core/or/circuitmux_ewma.c b/src/core/or/circuitmux_ewma.c index 3f83c3fd5..606b755e2 100644 --- a/src/core/or/circuitmux_ewma.c +++ b/src/core/or/circuitmux_ewma.c @@ -147,7 +147,9 @@ TO_EWMA_POL_DATA(circuitmux_policy_data_t *pol) { if (!pol) return NULL; else { - tor_assert(pol->magic == EWMA_POL_DATA_MAGIC); + tor_assertf(pol->magic == EWMA_POL_DATA_MAGIC, + "Mismatch: %"PRIu32" != %"PRIu32, + pol->magic, EWMA_POL_DATA_MAGIC); return DOWNCAST(ewma_policy_data_t, pol); } } @@ -162,7 +164,9 @@ TO_EWMA_POL_CIRC_DATA(circuitmux_policy_circ_data_t *pol) { if (!pol) return NULL; else { - tor_assert(pol->magic == EWMA_POL_CIRC_DATA_MAGIC); + tor_assertf(pol->magic == EWMA_POL_CIRC_DATA_MAGIC, + "Mismatch: %"PRIu32" != %"PRIu32, + pol->magic, EWMA_POL_CIRC_DATA_MAGIC); return DOWNCAST(ewma_policy_circ_data_t, pol); } } @@ -295,6 +299,7 @@ ewma_free_cmux_data(circuitmux_t *cmux, pol = TO_EWMA_POL_DATA(pol_data);

smartlist_free(pol->active_circuit_pqueue); + pol->base_.magic = 0xDEAD901C; tor_free(pol); }

@@ -361,7 +366,7 @@ ewma_free_circ_data(circuitmux_t *cmux, if (!pol_circ_data) return;

cdata = TO_EWMA_POL_CIRC_DATA(pol_circ_data); - + cdata->base_.magic = 0xDEADC14C; tor_free(cdata); }