talloc: split the handling of FLAG_POOL/FLAG_POOLMEM in _talloc_free_internal

The optimization of the object_count == 1 case should only happen
for when we're not destroying the pool itself. And it should only
happen if the pool itself is still valid.

If the pool isn't valid (it has TALLOC_FLAG_FREE),
object_count == 1 does not mean that the pool is the last object,
which can happen if you use talloc_steal/move() on memory
from the pool and then free the pool itself.

Thanks to Volker for noticing this!

metze

1 files changed, 66 insertions, 32 deletions

diff --git a/lib/talloc/talloc.c b/lib/talloc/talloc.c
index 2a956dcf0d4..0efeb7a7ada 100644
--- a/lib/talloc/talloc.c
+++ b/lib/talloc/talloc.c
@@ -709,6 +709,65 @@ _PUBLIC_ void *_talloc_reference_loc(const void *context, const void *ptr, const
 
 static void *_talloc_steal_internal(const void *new_ctx, const void *ptr);
 
+static inline void _talloc_free_poolmem(struct talloc_chunk *tc,
+					const char *location)
+{
+	struct talloc_chunk *pool;
+	void *next_tc;
+	unsigned int *pool_object_count;
+
+	pool = (struct talloc_chunk *)tc->pool;
+	next_tc = TC_POOLMEM_NEXT_CHUNK(tc);
+
+	tc->flags |= TALLOC_FLAG_FREE;
+
+	/* we mark the freed memory with where we called the free
+	 * from. This means on a double free error we can report where
+	 * the first free came from
+	 */
+	tc->name = location;
+
+	TC_INVALIDATE_FULL_CHUNK(tc);
+
+	pool_object_count = talloc_pool_objectcount(pool);
+
+	if (unlikely(*pool_object_count == 0)) {
+		talloc_abort("Pool object count zero!");
+		return;
+	}
+
+	*pool_object_count -= 1;
+
+	if (unlikely(*pool_object_count == 1 && !(pool->flags & TALLOC_FLAG_FREE))) {
+		/*
+		 * if there is just one object left in the pool
+		 * and pool->flags does not have TALLOC_FLAG_FREE,
+		 * it means this is the pool itself and
+		 * the rest is available for new objects
+		 * again.
+		 */
+		pool->pool = TC_POOL_FIRST_CHUNK(pool);
+		TC_INVALIDATE_POOL(pool);
+	} else if (unlikely(*pool_object_count == 0)) {
+		/*
+		 * we mark the freed memory with where we called the free
+		 * from. This means on a double free error we can report where
+		 * the first free came from
+		 */
+		pool->name = location;
+
+		TC_INVALIDATE_FULL_CHUNK(pool);
+		free(pool);
+	} else if (pool->pool == next_tc) {
+		/*
+		 * if pool->pool still points to end of
+		 * 'tc' (which is stored in the 'next_tc' variable),
+		 * we can reclaim the memory of 'tc'.
+		 */
+		pool->pool = tc;
+	}
+}
+
 /* 
    internal talloc_free call
 */
@@ -823,21 +882,10 @@ static inline int _talloc_free_internal(void *ptr, const char *location)
 	 */	 
 	tc->name = location;
 
-	if (tc->flags & (TALLOC_FLAG_POOL|TALLOC_FLAG_POOLMEM)) {
-		struct talloc_chunk *pool;
-		void *next_tc = NULL;
+	if (tc->flags & TALLOC_FLAG_POOL) {
 		unsigned int *pool_object_count;
 
-		if (unlikely(tc->flags & TALLOC_FLAG_POOL)) {
-			pool = tc;
-		} else {
-			pool = (struct talloc_chunk *)tc->pool;
-			next_tc = TC_POOLMEM_NEXT_CHUNK(tc);
-
-			TC_INVALIDATE_FULL_CHUNK(tc);
-		}
-
-		pool_object_count = talloc_pool_objectcount(pool);
+		pool_object_count = talloc_pool_objectcount(tc);
 
 		if (unlikely(*pool_object_count == 0)) {
 			talloc_abort("Pool object count zero!");
@@ -846,26 +894,12 @@ static inline int _talloc_free_internal(void *ptr, const char *location)
 
 		*pool_object_count -= 1;
 
-		if (unlikely(*pool_object_count == 1)) {
-			/*
-			 * if there is just object left in the pool
-			 * it means this is the pool itself and
-			 * the rest is available for new objects
-			 * again.
-			 */
-			pool->pool = TC_POOL_FIRST_CHUNK(pool);
-			TC_INVALIDATE_POOL(pool);
-		} else if (unlikely(*pool_object_count == 0)) {
-			TC_INVALIDATE_FULL_CHUNK(pool);
-			free(pool);
-		} else if (pool->pool == next_tc) {
-			/*
-			 * if pool->pool still points to end of
-			 * 'tc' (which is stored in the 'next_tc' variable),
-			 * we can reclaim the memory of 'tc'.
-			 */
-			pool->pool = tc;
+		if (unlikely(*pool_object_count == 0)) {
+			TC_INVALIDATE_FULL_CHUNK(tc);
+			free(tc);
 		}
+	} else if (tc->flags & TALLOC_FLAG_POOLMEM) {
+		_talloc_free_poolmem(tc, location);
 	} else {
 		TC_INVALIDATE_FULL_CHUNK(tc);
 		free(tc);