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 63BF630F55B; Thu, 16 Jul 2026 15:37:09 +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=1784216230; cv=none; b=iHAarfZ1v+VgG58iPY1u8R4Sn1POEGoP+sm3mrw3kGHzjtWvdL3k1lWDgKp/88OpHwbE10VK72YU73uKz8BiOYBWz6BmPbElYKO8qgzWNrsU7t3oDbktjWt9FOu/ls2sEHHPIeNyQHzszoo3fK+f7PlAKSP4DFHNt0lUquLrCjg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784216230; c=relaxed/simple; bh=7FQkFjFCRyBVR+FvZ4xm8/TMVQDGDuAYw6VlkHyBKsI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RZHRP18lRNEGR7JM9lDWv9WyLezgg4+8kDhu0UzIz6BhhXuqyHwkM4bXPS2jlTeEwmvCDpgM3N4IdhGo3M/0KPLRlnbGyIIQJiJ99gR+qKhlTDlJVzyPOCeYD4ynC+PX3XKiJpExGrZmw6EBUuzeXGcCfvjqeP+X9r+QwVpbzCA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mB20yKhC; 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="mB20yKhC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 506101F000E9; Thu, 16 Jul 2026 15:37:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784216229; bh=9yMSEpcxokYlbr1pI3HxhioNdh8t09miV4mATsF1wF8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mB20yKhCGBrLytuyCNFCXLHU7+i/U2LnVIbXRbVhWjZBipv3XhPm7r80NXZ1Zo/J3 OKR41JOGl103KN7CBncAxH1XbfN2xIOYbgw3646rZYdNJ4qhrqZg1P4fXKc3MOxygt wjGgGUNUdL3GlJ/ixt77FyhxBf3VJ38P3AH8UdSD9zpSVXMuKORkFpUnyJhI9raWQ9 CEAOxV5/rdnoBXmfZOe+0ZRwRbyIVfxlHpv251vB5z6Evm9hLk7/jJCwQhiTJ6ilg8 mqsTWbJPCIcgEi34RvPhInzDrOkYenUbW2ywlBci0+DcH2HoPHun1/wqo4AC8Xy4qF ytGhm/1xKkWLw== 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 6.1.y 4/7] ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc Date: Thu, 16 Jul 2026 11:37:01 -0400 Message-ID: <20260716153704.583869-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260716153704.583869-1-sashal@kernel.org> References: <2026071414-kosher-parsley-920b@gregkh> <20260716153704.583869-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@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/smb/server/connection.c | 1 + fs/smb/server/smb2pdu.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c index 92d8a0d898ebd7..ae21de810e5870 100644 --- a/fs/smb/server/connection.c +++ b/fs/smb/server/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/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index ff1615f9d63b69..e0f0e738a2e49f 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -1909,7 +1909,7 @@ 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