[PATCH 2/4] staging: rtl8723bs: fix double free when register_netdev() fails

[Yi Cong]

From: Yi Cong <yicong@xxxxxxxxxx>

When register_netdev() fails, the error_register_netdev label in
_rtw_drv_register_netdev() frees the adapter and netdev via
rtw_free_drv_sw()/rtw_free_netdev() and then returns _FAIL.

The caller rtw_drv_init(), however, still holds a non-NULL if1 on this
failure path and jumps to free_if1, where rtw_sdio_if1_deinit() invokes
rtw_free_drv_sw() and rtw_free_netdev() again on the same already-freed
objects, resulting in a double free / use-after-free.

Drop the freeing from error_register_netdev and let rtw_sdio_if1_deinit()
perform the tear-down, which is the single owner for this path.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Signed-off-by: Yi Cong <yicong@xxxxxxxxxx>
---
 drivers/staging/rtl8723bs/os_dep/os_intfs.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/rtl8723bs/os_dep/os_intfs.c b/drivers/staging/rtl8723bs/os_dep/os_intfs.c
index f31196f54b3e..ac401042faf4 100644
--- a/drivers/staging/rtl8723bs/os_dep/os_intfs.c
+++ b/drivers/staging/rtl8723bs/os_dep/os_intfs.c
@@ -773,10 +773,12 @@ static int _rtw_drv_register_netdev(struct adapter *padapter, char *name)
 
 error_register_netdev:
 
-	rtw_free_drv_sw(padapter);
-
-	rtw_free_netdev(pnetdev);
-
+	/* Let the caller (rtw_drv_init -> rtw_sdio_if1_deinit) release the
+	 * adapter and netdev. Freeing them here would lead to a double free:
+	 * rtw_drv_init() still holds a non-NULL if1 and calls
+	 * rtw_sdio_if1_deinit(), which invokes rtw_free_drv_sw() and
+	 * rtw_free_netdev() again on the already-freed objects.
+	 */
 	return ret;
 }
 
-- 
2.25.1