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libxl: Protect access to libxlLogger files hash table

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The hash table of log file objects in libxlLogger is not protected against
concurrent access. It is possible for one thread to remove an entry while
another is updating it. Add a mutex to the libxlLogger object and lock it
when accessing the files hash table.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
This commit is contained in:
Jim Fehlig 2021-11-18 12:03:20 -07:00
parent 5c5df5310f
commit a7a03324d8
1 changed files with 14 additions and 0 deletions
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14
src/libxl/libxl_logger.c
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@ -28,6 +28,7 @@
#include "util/virfile.h"
#include "util/virhash.h"
#include "util/virstring.h"
#include "util/virthread.h"
#include "util/virtime.h"
#define VIR_FROM_THIS VIR_FROM_LIBXL
@ -43,6 +44,7 @@ struct xentoollog_logger_libvirt {
/* map storing the opened fds: "domid" -> FILE* */
GHashTable *files;
virMutex tableLock;
FILE *defaultLogFile;
};
@ -85,7 +87,9 @@ libvirt_vmessage(xentoollog_logger *logger_in,
start = start + 9;
*end = '\0';
virMutexLock(&lg->tableLock);
domainLogFile = virHashLookup(lg->files, start);
virMutexUnlock(&lg->tableLock);
if (domainLogFile)
logFile = domainLogFile;
@ -155,6 +159,11 @@ libxlLoggerNew(const char *logDir, virLogPriority minLevel)
if ((logger.defaultLogFile = fopen(path, "a")) == NULL)
return NULL;
if (virMutexInit(&logger.tableLock) < 0) {
VIR_FORCE_FCLOSE(logger.defaultLogFile);
return NULL;
}
logger.files = virHashNew(libxlLoggerFileFree);
return XTL_NEW_LOGGER(libvirt, logger);
@ -167,6 +176,7 @@ libxlLoggerFree(libxlLogger *logger)
if (logger->defaultLogFile)
VIR_FORCE_FCLOSE(logger->defaultLogFile);
g_clear_pointer(&logger->files, g_hash_table_unref);
virMutexDestroy(&logger->tableLock);
xtl_logger_destroy(xtl_logger);
}
@ -188,7 +198,9 @@ libxlLoggerOpenFile(libxlLogger *logger,
path, g_strerror(errno));
return;
}
virMutexLock(&logger->tableLock);
ignore_value(virHashAddEntry(logger->files, domidstr, logFile));
virMutexUnlock(&logger->tableLock);
/* domain_config is non NULL only when starting a new domain */
if (domain_config) {
@ -203,5 +215,7 @@ libxlLoggerCloseFile(libxlLogger *logger, int id)
g_autofree char *domidstr = NULL;
domidstr = g_strdup_printf("%d", id);
virMutexLock(&logger->tableLock);
ignore_value(virHashRemoveEntry(logger->files, domidstr));
virMutexUnlock(&logger->tableLock);
}