From 1fca8038e9f10bc14eb3484d212b3f03b49ac3f5 Mon Sep 17 00:00:00 2001 From: Marios Makassikis Date: Thu, 6 May 2021 11:41:54 +0900 Subject: [PATCH] cifsd: Fix potential null-ptr-deref in destroy_previous_session() The user field in the session structure is allocated when the client is authenticated. If the client explicitly logs off, the user field is freed, but the session is kept around in case the user reconnects. If the TCP connection hasn't been closed and the client sends a session setup with a PreviousSessionId set, destroy_previous_session() will be called to check if the session needs to be cleaned up. Signed-off-by: Marios Makassikis Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- fs/cifsd/smb2pdu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/cifsd/smb2pdu.c b/fs/cifsd/smb2pdu.c index 54df9a3..ebae992 100644 --- a/fs/cifsd/smb2pdu.c +++ b/fs/cifsd/smb2pdu.c @@ -619,7 +619,8 @@ static void destroy_previous_session(struct ksmbd_user *user, u64 id) prev_user = prev_sess->user; - if (strcmp(user->name, prev_user->name) || + if (!prev_user || + strcmp(user->name, prev_user->name) || user->passkey_sz != prev_user->passkey_sz || memcmp(user->passkey, prev_user->passkey, user->passkey_sz)) { put_session(prev_sess); -- 2.7.4