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| author | Nick Mathewson <nickm@torproject.org> | 2009-08-20 11:51:34 -0400 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2009-08-20 11:55:33 -0400 |
| commit | 9d11827780d15d8b398d8ce6b04110a4dea5e980 (patch) | |
| tree | 54e6dc83f381e1595cfb286be3bf078807736d9e | |
| parent | c9b8a4a133780cb2ab3847292284a6e9292b70d1 (diff) | |
| download | tor-9d11827780d15d8b398d8ce6b04110a4dea5e980.tar.gz tor-9d11827780d15d8b398d8ce6b04110a4dea5e980.zip | |
Fix a rare infinite-recursion bug when shutting down.
Once we had called log_free_all(), anything that tried to log a
message (like a failed tor_assert()) would fail like this:
1. The logging call eventually invokes the _log() function.
2. _log() calls tor_mutex_lock(log_mutex).
3. tor_mutex_lock(m) calls tor_assert(m).
4. Since we freed the log_mutex, tor_assert() fails, and tries to
log its failure.
5. GOTO 1.
Now we allocate the mutex statically, and never destroy it on
shutdown.
Bugfix on 0.2.0.16-alpha, which introduced the log mutex.
This bug was found by Matt Edman.
| -rw-r--r-- | ChangeLog | 3 | ||||
| -rw-r--r-- | src/common/log.c | 18 |
2 files changed, 14 insertions, 7 deletions
@@ -15,6 +15,9 @@ Changes in version 0.2.1.20 - 2009-??-?? - Fix a signed/unsigned compile warning in 0.2.1.19. - Fix possible segmentation fault on directory authorities. Bugfix on 0.2.1.14-rc. + - Fix an extremely infinite recursion bug that could occur if we tried + to log a message after shutting down the log subsystem. Found by Matt + Edman. Bugfix on 0.2.0.16-alpha. Changes in version 0.2.1.19 - 2009-07-28 diff --git a/src/common/log.c b/src/common/log.c index a7b0c12c4a..ea09fca167 100644 --- a/src/common/log.c +++ b/src/common/log.c @@ -94,7 +94,8 @@ should_log_function_name(log_domain_mask_t domain, int severity) } /** A mutex to guard changes to logfiles and logging. */ -static tor_mutex_t *log_mutex = NULL; +static tor_mutex_t log_mutex; +static int log_mutex_initialized = 0; /** Linked list of logfile_t. */ static logfile_t *logfiles = NULL; @@ -105,9 +106,9 @@ static int syslog_count = 0; #endif #define LOCK_LOGS() STMT_BEGIN \ - tor_mutex_acquire(log_mutex); \ + tor_mutex_acquire(&log_mutex); \ STMT_END -#define UNLOCK_LOGS() STMT_BEGIN tor_mutex_release(log_mutex); STMT_END +#define UNLOCK_LOGS() STMT_BEGIN tor_mutex_release(&log_mutex); STMT_END /** What's the lowest log level anybody cares about? Checking this lets us * bail out early from log_debug if we aren't debugging. */ @@ -448,8 +449,9 @@ logs_free_all(void) log_free(victim); } tor_free(appname); - tor_mutex_free(log_mutex); - log_mutex = NULL; + + /* We _could_ destroy the log mutex here, but that would screw up any logs + * that happened between here and the end of execution. */ } /** Remove and free the log entry <b>victim</b> from the linked-list @@ -545,8 +547,10 @@ add_stream_log(const log_severity_list_t *severity, void init_logging(void) { - if (!log_mutex) - log_mutex = tor_mutex_new(); + if (!log_mutex_initialized) { + tor_mutex_init(&log_mutex); + log_mutex_initialized = 1; + } } /** Add a log handler to receive messages during startup (before the real |