misc: fastrpc: Don't remove map on creater_process and device_release

commit 5bb96c8f9268e2fdb0e5321cbc358ee5941efc15 upstream.

Do not remove the map from the list on error path in
fastrpc_init_create_process, instead call fastrpc_map_put, to avoid
use-after-free. Do not remove it on fastrpc_device_release either,
call fastrpc_map_put instead.

The fastrpc_free_map is the only proper place to remove the map.
This is called only after the reference count is 0.

Fixes: b49f6d83e290 ("misc: fastrpc: Fix a possible double free")
Cc: stable <stable@kernel.org>
Co-developed-by: Ola Jeppsson <ola@snap.com>
Signed-off-by: Ola Jeppsson <ola@snap.com>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20221124174941.418450-3-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index fc2173c..9ecbf67 100644 (file)
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -316,6 +316,13 @@ static void fastrpc_free_map(struct kref *ref)
                dma_buf_put(map->buf);
        }
 
+       if (map->fl) {
+               spin_lock(&map->fl->lock);
+               list_del(&map->node);
+               spin_unlock(&map->fl->lock);
+               map->fl = NULL;
+       }
+
        kfree(map);
 }
 
@@ -1266,12 +1273,7 @@ err_invoke:
        fl->init_mem = NULL;
        fastrpc_buf_free(imem);
 err_alloc:
-       if (map) {
-               spin_lock(&fl->lock);
-               list_del(&map->node);
-               spin_unlock(&fl->lock);
-               fastrpc_map_put(map);
-       }
+       fastrpc_map_put(map);
 err:
        kfree(args);
 
@@ -1347,10 +1349,8 @@ 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);
-       }
 
        list_for_each_entry_safe(buf, b, &fl->mmaps, node) {
                list_del(&buf->node);