[102/105] ext4: fix a double free in ext4_register_li_request

[Greg KH]

2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tao Ma <boyu.mt@xxxxxxxxxx>

commit 46e4690bbd9a4f8d9e7c4f34e34b48f703ad47e0 upstream.

In ext4_register_li_request, we malloc a ext4_li_request and
inserts it into ext4_li_info->li_request_list. In case of any
error later, we free it in the end.  But if we have some error
in ext4_run_lazyinit_thread, the whole li_request_list will be
dropped and freed in it. So we will double free this ext4_li_request.

This patch just sets elr to NULL after it is inserted to the list
so that the latter kfree won't double free it.

Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx>
Reviewed-by: Lukas Czerner <lczerner@xxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/ext4/super.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2978,6 +2978,12 @@ static int ext4_register_li_request(stru
 	mutex_unlock(&ext4_li_info->li_list_mtx);
 
 	sbi->s_li_request = elr;
+	/*
+	 * set elr to NULL here since it has been inserted to
+	 * the request_list and the removal and free of it is
+	 * handled by ext4_clear_request_list from now on.
+	 */
+	elr = NULL;
 
 	if (!(ext4_li_info->li_state & EXT4_LAZYINIT_RUNNING)) {
 		ret = ext4_run_lazyinit_thread();


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/