cifs: Fix memory and information leak in smb3_reconfigure()

[PATCH] cifs: Fix memory and information leak in smb3_reconfigure()

Posted by Zilin Guan 1 month, 2 weeks ago

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@seu.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

Re: [PATCH] cifs: Fix memory and information leak in smb3_reconfigure()

Posted by ChenXiaoSong 1 month, 2 weeks ago

Good catch. Looks good to me.

Thanks,
ChenXiaoSong.

On 12/24/25 11:21 PM, Zilin Guan wrote:
> 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@seu.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;
>   	}
>