@@ -245,19 +245,21 @@ static void fastrpc_free_map(struct kref *ref)
dma_buf_put(map->buf);
}
+ list_del(&map->node);
+
kfree(map);
}
static void fastrpc_map_put(struct fastrpc_map *map)
{
- if (map)
- kref_put(&map->refcount, fastrpc_free_map);
+ spin_lock(&map->fl->lock);
+ kref_put(&map->refcount, fastrpc_free_map);
+ spin_unlock(&map->fl->lock);
}
static void fastrpc_map_get(struct fastrpc_map *map)
{
- if (map)
- kref_get(&map->refcount);
+ kref_get(&map->refcount);
}
static int fastrpc_map_find(struct fastrpc_user *fl, int fd,
@@ -351,8 +353,10 @@ static void fastrpc_context_free(struct kref *ref)
ctx = container_of(ref, struct fastrpc_invoke_ctx, refcount);
cctx = ctx->cctx;
- for (i = 0; i < ctx->nscalars; i++)
- fastrpc_map_put(ctx->maps[i]);
+ for (i = 0; i < ctx->nscalars; i++) {
+ if (ctx->maps[i])
+ fastrpc_map_put(ctx->maps[i]);
+ }
if (ctx->buf)
fastrpc_buf_free(ctx->buf);
@@ -1103,12 +1107,8 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
fl->init_mem = NULL;
fastrpc_buf_free(imem);
err_alloc:
- if (map) {
- spin_lock(&fl->lock);
- list_del(&map->node);
- spin_unlock(&fl->lock);
+ if (map)
fastrpc_map_put(map);
- }
err:
kfree(args);
@@ -1185,10 +1185,9 @@ static int fastrpc_device_release(struct inode *inode, struct file *file)
fastrpc_context_put(ctx);
}
- list_for_each_entry_safe(map, m, &fl->maps, node) {
- list_del(&map->node);
+ list_for_each_entry_safe(map, m, &fl->maps, node)
fastrpc_map_put(map);
- }
+ WARN_ON(!list_empty(&fl->maps));
list_for_each_entry_safe(buf, b, &fl->mmaps, node) {
list_del(&buf->node);
This fixes the incredibly broken behavior of fastrpc_context_free(), which calls fastrpc_map_put() but does not remove the map from the list when it is free'd, causing use-after-free errors. fl->lock needs to be held not just for list_del(), but also kref_put, to avoid a race condition with fastrpc_map_find() logic. Signed-off-by: Jonathan Marek <jonathan@marek.ca> --- drivers/misc/fastrpc.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-)