From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 95FCD446072; Thu, 16 Jul 2026 18:22:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784226139; cv=none; b=ouqEqDtU/be35/uTdowrnDE9uBCKHX3EoGDUAHjPQPmUjd8U/IELDd++6Qk2rpyUU15aS3VMcTnDxyUGGvXLqnyv8jYqmSgWHwNco17mC92RZ9rsWJCTrqnGoU446TQLsnrUxi5cfcqi6WpCKoI8+c/SRBzdieIE1IV+/yx9yFM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784226139; c=relaxed/simple; bh=kNPi6pA+SRJTGfGulqUHyhvPI3unB2m0lySgnyzDc9k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ba5dWBdSxIO0lBauN8UA6XwNyPuO4EgxkVd+ZDsKFiwTWwyxPQnxCOko0BNwE8zPiJH4CZHY3XVE3rOdLKqg5TP4+PcrIZMXoJYuIAqFBfQ1GGcghdOyE5Bmpx6tTGe/DzjQ7CxrsnfJ6WSV/HkJpT3jZaNeRpblQGDnTXNqw14= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ImDq0oFL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ImDq0oFL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D17D51F00ACF; Thu, 16 Jul 2026 18:22:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784226130; bh=Cw1/b6JLbNyPN4ogntGJaoqzdeHTObSMsULLRlJB8Z4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ImDq0oFL2XnUrXjlrzGzkeKd3xuUWLwU1k+D13OjLxGq0tZe8G4FteCqoHXp/iJLE E/tmT20QVkcMa7OIi67boWC61/2QDDMbVrQ+UTu230Ljfw1RZAGm8EYkMbtwn+h2bk yA4AO7Ks61JGvvHAM/iAR9SZTTL3/btBXCJjry/zZI7kFfT/ia/GC+Tfcd8FesYbmr sJ8OdaUFlJe3Ro4ZzLGWhCYqiLIQw79seWj8wHfuwWRdxKoH9J+KtoHix8s2lkNEX/ 7fPIhVpTik3fPCs520/OrCJMB4bpJ/4sIifRJxkW4S5fiAW6SwSms331Q/EhybwPRy TyQgkR5GL79EA== From: Sasha Levin To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , Namjae Jeon , Steve French , Sergey Senozhatsky , Tom Talpey , linux-cifs@vger.kernel.org, stable@kernel.org, Steve French , Sasha Levin Subject: [PATCH 5.15.y 4/7] ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc Date: Thu, 16 Jul 2026 14:22:02 -0400 Message-ID: <20260716182205.921233-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260716182205.921233-1-sashal@kernel.org> References: <2026071415-rambling-chooser-b760@gregkh> <20260716182205.921233-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman [ Upstream commit ad0057fb91218914d6c98268718ceb9d59b388e1 ] The kernel ASN.1 BER decoder calls action callbacks incrementally as it walks the input. When ksmbd_decode_negTokenInit() reaches the mechToken [2] OCTET STRING element, ksmbd_neg_token_alloc() allocates conn->mechToken immediately via kmemdup_nul(). If a later element in the same blob is malformed, then the decoder will return nonzero after the allocation is already live. This could happen if mechListMIC [3] overrunse the enclosing SEQUENCE. decode_negotiation_token() then sets conn->use_spnego = false because both the negTokenInit and negTokenTarg grammars failed. The cleanup at the bottom of smb2_sess_setup() is gated on use_spnego: if (conn->use_spnego && conn->mechToken) { kfree(conn->mechToken); conn->mechToken = NULL; } so the kfree is skipped, causing the mechToken to never be freed. This codepath is reachable pre-authentication, so untrusted clients can cause slow memory leaks on a server without even being properly authenticated. Fix this up by not checking check for use_spnego, as it's not required, so the memory will always be properly freed. At the same time, always free the memory in ksmbd_conn_free() incase some other failure path forgot to free it. Cc: Namjae Jeon Cc: Steve French Cc: Sergey Senozhatsky Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman Acked-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: c1016dd1d8b2 ("ksmbd: track the connection owning a byte-range lock") Signed-off-by: Sasha Levin --- fs/ksmbd/connection.c | 1 + fs/ksmbd/smb2pdu.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/ksmbd/connection.c b/fs/ksmbd/connection.c index 63815c4df1333e..524caba512e79a 100644 --- a/fs/ksmbd/connection.c +++ b/fs/ksmbd/connection.c @@ -39,6 +39,7 @@ void ksmbd_conn_free(struct ksmbd_conn *conn) xa_destroy(&conn->sessions); kvfree(conn->request_buf); kfree(conn->preauth_info); + kfree(conn->mechToken); kfree(conn); } diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index a31a1561540960..af1e386cedb43b 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -1920,7 +1920,7 @@ int smb2_sess_setup(struct ksmbd_work *work) else if (rc) rsp->hdr.Status = STATUS_LOGON_FAILURE; - if (conn->use_spnego && conn->mechToken) { + if (conn->mechToken) { kfree(conn->mechToken); conn->mechToken = NULL; } -- 2.53.0