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libsepol: cil: cil_strpool: Allow multiple strpool users.

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cil_strpool currently provides an interface to a statically stored
global data structure.  This interface does not accomodate multiple
consumers, however, as two calls to cil_strpool_init() will lead to a
memory leak and a call to cil_strpool_destroy() by one consumer will
remove data from use by others, and subsequently lead to a segfault on
the next cil_strpool_destroy() invocation.

Add a reference counter so that the strpool is only initialized once and
protect the exported interface with a mutex.

Tested by calling cil_db_init() on two cil_dbs and then calling
cil_db_destroy() on each.

Signed-off-by: Daniel Cashman <dcashman@android.com>
This commit is contained in:
dcashman 2016-10-18 14:31:51 -07:00 committed by James Carter
parent ff47e2d921
commit d7cb38ff87
1 changed files with 24 additions and 4 deletions
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28
libsepol/cil/src/cil_strpool.c
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@ -27,6 +27,7 @@
* either expressed or implied, of Tresys Technology, LLC.
*/
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
@ -40,6 +41,8 @@ struct cil_strpool_entry {
char *str;
};
static pthread_mutex_t cil_strpool_mutex = PTHREAD_MUTEX_INITIALIZER;
static unsigned int cil_strpool_readers = 0;
static hashtab_t cil_strpool_tab = NULL;
static unsigned int cil_strpool_hash(hashtab_t h, hashtab_key_t key)
@ -68,16 +71,21 @@ char *cil_strpool_add(const char *str)
{
struct cil_strpool_entry *strpool_ref = NULL;
pthread_mutex_lock(&cil_strpool_mutex);
strpool_ref = hashtab_search(cil_strpool_tab, (hashtab_key_t)str);
if (strpool_ref == NULL) {
strpool_ref = cil_malloc(sizeof(*strpool_ref));
strpool_ref->str = cil_strdup(str);
int rc = hashtab_insert(cil_strpool_tab, (hashtab_key_t)strpool_ref->str, strpool_ref);
if (rc != SEPOL_OK) {
pthread_mutex_unlock(&cil_strpool_mutex);
(*cil_mem_error_handler)();
pthread_mutex_lock(&cil_strpool_mutex);
}
}
pthread_mutex_unlock(&cil_strpool_mutex);
return strpool_ref->str;
}
@ -91,14 +99,26 @@ static int cil_strpool_entry_destroy(hashtab_key_t k __attribute__ ((unused)), h
void cil_strpool_init(void)
{
cil_strpool_tab = hashtab_create(cil_strpool_hash, cil_strpool_compare, CIL_STRPOOL_TABLE_SIZE);
pthread_mutex_lock(&cil_strpool_mutex);
if (cil_strpool_tab == NULL) {
(*cil_mem_error_handler)();
cil_strpool_tab = hashtab_create(cil_strpool_hash, cil_strpool_compare, CIL_STRPOOL_TABLE_SIZE);
if (cil_strpool_tab == NULL) {
pthread_mutex_unlock(&cil_strpool_mutex);
(*cil_mem_error_handler)();
return;
}
}
cil_strpool_readers++;
pthread_mutex_unlock(&cil_strpool_mutex);
}
void cil_strpool_destroy(void)
{
hashtab_map(cil_strpool_tab, cil_strpool_entry_destroy, NULL);
hashtab_destroy(cil_strpool_tab);
pthread_mutex_lock(&cil_strpool_mutex);
cil_strpool_readers--;
if (cil_strpool_readers == 0) {
hashtab_map(cil_strpool_tab, cil_strpool_entry_destroy, NULL);
hashtab_destroy(cil_strpool_tab);
}
pthread_mutex_unlock(&cil_strpool_mutex);
}