tor

commit 4db610d6d96f711d3bd1e8f2a0080d83f1f5fcd0
parent 7e055c383c1204847dcf842ed39fea0e8d8d92d8
Author: David Goulet <dgoulet@torproject.org>
Date:   Tue, 10 Jan 2023 09:24:09 -0500

state: Fix segfault on malformed file

Having no TotalBuildTimes along a positive CircuitBuildAbandonedCount
count lead to a segfault. We check for that condition and then BUG + log
warn if that is the case.

It should never happened in theory but if someone modified their state
file, it can lead to this problem so instead of segfaulting, warn.

Fixes #40437

Signed-off-by: David Goulet <dgoulet@torproject.org>

Diffstat:
A
changes/ticket40437
 | 
4
++++
M
src/core/or/circuitstats.c
 | 
12
++++++++++++

2 files changed, 16 insertions(+), 0 deletions(-)
diff --git a/changes/ticket40437 b/changes/ticket40437
@@ -0,0 +1,4 @@
+  o Minor bugfixes (state file):
+    - Avoid a segfault if the state file doesn't contains TotalBuildTimes along
+      CircuitBuildAbandonedCount being above 0. Fixes bug 40437; bugfix on
+      0.3.5.1-alpha.
diff --git a/src/core/or/circuitstats.c b/src/core/or/circuitstats.c
@@ -1018,6 +1018,18 @@ circuit_build_times_parse_state(circuit_build_times_t *cbt,
     return 0;
   }
 
+  /* We had a case where someone removed their TotalBuildTimes from the state
+   * files while having CircuitBuildAbandonedCount above 0 leading to a
+   * segfault (#40437). Simply bug on it and return an error so at least the
+   * user will learn that they broke the state file. */
+  if (BUG(state->TotalBuildTimes <= 0 &&
+          state->CircuitBuildAbandonedCount > 0)) {
+    log_warn(LD_GENERAL, "CircuitBuildAbandonedCount count is above 0 but "
+                         "no TotalBuildTimes have been found. Unable to "
+                         "parse broken state file");
+    return -1;
+  }
+
   /* build_time_t 0 means uninitialized */
   loaded_times = tor_calloc(state->TotalBuildTimes, sizeof(build_time_t));