mainline inclusion from mainline-v7.2-rc5 commit c74801ee524f477c174a1899782b6c3b6918d407 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16939 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- In ntlm_authenticate(), destroy_previous_session() is called using a user pointer resolved from the client-supplied NTLM blob username field before the NTLMv2 response is validated. An authenticated attacker can set the NTLM blob username to match a victim account and set PreviousSessionId to the victim's session ID; destroy_previous_session() destroys the victim's session while ksmbd_decode_ntlmssp_auth_blob() subsequently rejects the request with -EPERM. Move destroy_previous_session() and the prev_id assignment to after ksmbd_decode_ntlmssp_auth_blob() returns success and use sess->user rather than the pre-authentication lookup result. This matches the ordering already used by krb5_authenticate(), where destroy_previous_session() is called only after ksmbd_krb5_authenticate() returns success. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/linux-cifs/20260702155449.3639773-1-james_montgomery... Signed-off-by: James Montgomery <james_montgomery@disroot.org> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Conflicts: fs/ksmbd/smb2pdu.c [ctx conflicts] Signed-off-by: Lai Zewei <laizewei3@huawei.com> --- fs/ksmbd/smb2pdu.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index ff3bcd2f7c46..d8262429e31b 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -1487,11 +1487,6 @@ static int ntlm_authenticate(struct ksmbd_work *work, return -EPERM; } - /* Check for previous session */ - prev_id = le64_to_cpu(req->PreviousSessionId); - if (prev_id && prev_id != sess->id) - destroy_previous_session(conn, user, prev_id); - if (sess->state == SMB2_SESSION_VALID) { /* * Reuse session if anonymous try to connect @@ -1526,6 +1521,10 @@ static int ntlm_authenticate(struct ksmbd_work *work, } } + prev_id = le64_to_cpu(req->PreviousSessionId); + if (prev_id && prev_id != sess->id) + destroy_previous_session(conn, sess->user, prev_id); + /* * If session state is SMB2_SESSION_VALID, We can assume * that it is reauthentication. And the user/password -- 2.52.0