linux-kernel - [PATCH] cifs: Fix memory and information leak in smb3

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Message-Id: <20251224152142.289149-1-zilin@seu.edu.cn>
Date: Wed, 24 Dec 2025 15:21:42 +0000
From: Zilin Guan <zilin@....edu.cn>
To: sfrench@...ba.org
Cc: pc@...guebit.org,
	ronniesahlberg@...il.com,
	sprasad@...rosoft.com,
	tom@...pey.com,
	bharathsm@...rosoft.com,
	linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org,
	linux-kernel@...r.kernel.org,
	jianhao.xu@....edu.cn,
	Zilin Guan <zilin@....edu.cn>
Subject: [PATCH] cifs: Fix memory and information leak in smb3_reconfigure()

In smb3_reconfigure(), if smb3_sync_session_ctx_passwords() fails, the
function returns immediately without freeing and erasing the newly
allocated new_password and new_password2. This causes both a memory leak
and a potential information leak.

Fix this by calling kfree_sensitive() on both password buffers before
returning in this error case.

Fixes: 0f0e357902957 ("cifs: during remount, make sure passwords are in sync")
Signed-off-by: Zilin Guan <zilin@....edu.cn>
---
 fs/smb/client/fs_context.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index c2de97e4ad59..d4291d3a9a48 100644
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -1139,6 +1139,8 @@ static int smb3_reconfigure(struct fs_context *fc)
 	rc = smb3_sync_session_ctx_passwords(cifs_sb, ses);
 	if (rc) {
 		mutex_unlock(&ses->session_mutex);
+		kfree_sensitive(new_password);
+		kfree_sensitive(new_password2);
 		return rc;
 	}
 
-- 
2.34.1