[PATCH 5.6 049/194] umh: fix memory leak on execve failure

Greg Kroah-Hartman
2020-05-18T18:13:53Z

From: Vincent Minet <v.minet@criteo.com>

[ Upstream commit db803036ada7d61d096783726f9771b3fc540370 ]

If a UMH process created by fork_usermode_blob() fails to execute,
a pair of struct file allocated by umh_pipe_setup() will leak.

Under normal conditions, the caller (like bpfilter) needs to manage the
lifetime of the UMH and its two pipes. But when fork_usermode_blob()
fails, the caller doesn't really have a way to know what needs to be
done. It seems better to do the cleanup ourselves in this case.

Fixes: 449325b52b7a ("umh: introduce fork_usermode_blob() helper")
Signed-off-by: Vincent Minet <v.minet@criteo.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/umh.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -475,6 +475,12 @@ static void umh_clean_and_save_pid(struc
{
struct umh_info *umh_info = info->data;

+ /* cleanup if umh_pipe_setup() was successful but exec failed */
+ if (info->pid && info->retval) {
+ fput(umh_info->pipe_to_umh);
+ fput(umh_info->pipe_from_umh);
+ }
+
argv_free(info->argv);
umh_info->pid = info->pid;
}