| Message ID | 1476826311-31992-1-git-send-email-dcashman@android.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On 10/18/2016 05:31 PM, Daniel Cashman wrote: > From: dcashman <dcashman@android.com> > > 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> Applied. Thanks, Jim > --- > libsepol/cil/src/cil_strpool.c | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) > > diff --git a/libsepol/cil/src/cil_strpool.c b/libsepol/cil/src/cil_strpool.c > index ad2a334..5b7df8c 100644 > --- a/libsepol/cil/src/cil_strpool.c > +++ b/libsepol/cil/src/cil_strpool.c > @@ -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); > } >
diff --git a/libsepol/cil/src/cil_strpool.c b/libsepol/cil/src/cil_strpool.c index ad2a334..5b7df8c 100644 --- a/libsepol/cil/src/cil_strpool.c +++ b/libsepol/cil/src/cil_strpool.c @@ -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); }