Commit 4b5c44e9 authored Nov 24, 2022 by Abel Vesa Committed by Greg Kroah-Hartman Jan 24, 2023

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: b49f6d83 ("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>

parent 04eb41ec

drivers/misc/fastrpc.c

+9 −9

Original line number	Diff line number	Diff line
		@@ -218,6 +218,13 @@ 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);
		}

		@@ -1080,12 +1087,7 @@ 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);
		fastrpc_map_put(map);
		}
		err:
		kfree(args);

		@@ -1161,10 +1163,8 @@ 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);
		}

		fastrpc_session_free(cctx, fl->sctx);
		fastrpc_channel_ctx_put(cctx);