From: Vincent Minet <v.minet@criteo.com>
Date: Thu, 7 May 2020 22:14:22 +0000 (+0200)
Subject: umh: fix memory leak on execve failure
X-Git-Tag: v5.7-rc6~16^2~32
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=db803036ada7d61d096783726f9771b3fc540370;p=users%2Fdwmw2%2Flinux.git

umh: fix memory leak on execve failure

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>
---

diff --git a/kernel/umh.c b/kernel/umh.c
index 7f255b5a8845a..20d51e0957e0d 100644
--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -475,6 +475,12 @@ static void umh_clean_and_save_pid(struct subprocess_info *info)
 {
 	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;
 }