shm: Remove refcount check which cannot be triggered

If the pool refcount reaches zero, it is freed, so accessing its members
is UB which ASan would catch.

Also simplify check for negative refcounts.

Signed-off-by: Sebastian Wick <sebastian.wick@redhat.com>

1 files changed, 2 insertions, 7 deletions

diff --git a/src/wayland-shm.c b/src/wayland-shm.c
index d22353c..27db8c6 100644
--- a/src/wayland-shm.c
+++ b/src/wayland-shm.c
@@ -143,17 +143,16 @@ shm_pool_unref(struct wl_shm_pool *pool, bool external)
 {
 	if (external) {
 		pool->external_refcount--;
-		if (!(pool->external_refcount >= 0))
+		if (pool->external_refcount < 0)
 			wl_abort("Requested to unref an external reference to "
 				 "pool but none found\n");
 		if (pool->external_refcount == 0)
 			shm_pool_finish_resize(pool);
 	} else {
 		pool->internal_refcount--;
-		if (!(pool->internal_refcount >= 0))
+		if (pool->internal_refcount < 0)
 			wl_abort("Requested to unref an internal reference to "
 				 "pool but none found\n");
-
 	}
 
 	if (pool->internal_refcount + pool->external_refcount > 0)
@@ -513,10 +512,6 @@ wl_shm_buffer_get_height(const struct wl_shm_buffer *buffer)
 WL_EXPORT struct wl_shm_pool *
 wl_shm_buffer_ref_pool(struct wl_shm_buffer *buffer)
 {
-	if (!(buffer->pool->internal_refcount +
-	       buffer->pool->external_refcount))
-		wl_abort("Can't get reference to pool that has been freed\n");
-
 	buffer->pool->external_refcount++;
 	return buffer->pool;
 }