From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793701045; b=QKSjL+0MhShNw8jVHqqHOlYGs1rT2s9iXOZcbwnK896kqzl23g1ChQTaCxgrRGYVcEFP QzDgjsgggBGp9WeqsZHBYAIhQDM7jdp1YaeJnduKzAmz1T8oeVhQmSC/sAN5lRvunK0nd JBIvsRGeitwXWD90rVBOjobMml3vw7I2aRwOQAXOigD9l5eIMuKtXehnY2FnpcXMxT+EK 7g4283iJVazMjSIQhfanhHBcKEhBBMQo3jH79aNLxe+aLzbeUUcXdPJ4uSFX6WG/dHhkM qZHQuyprAB04KcCFlF1Jyhg57EP+k9WF70VpJVyBreauy4mCq1xsn1DzyRB0ZMVfxNg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793701045; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=HpuhWfRnhDWwgGiVmFHq8YO9RwBFI28MytzQ8eKOoHg=; b=nKVPfUN4oz3LgVjPt6YRDwgxstOQy9eOYahOgquMRkKJPl4kZvNEkzGKe4n6bKwfQ6lP 0Xz/3t2uem2KQ/oKLatJ/JTCLPDIqF1E8BEExBhMs9P+Dte8hG4S/pC2G47Wltd4+AnaG 2/KqxEqnIAe6+rHGboRwjjuXz35cZVcD+MjDwZLfdTZIhw3vxPIPaqk4zW6CQ866/pxRf VFemO8OLtCMvH7js5edSSfZsk/IRWz+hssj2hHRO1w1fhsVIX4KrD7EExkVDDDZ9XhKhM 63iaFY/RL1tUhXToL5Dqtpyy9v0o/2W2znbrNgxVSESlPYtbnblt+lGZhmfHhgZARPw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=nbmowXKf; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6D162606EEA9 for ; Tue, 3 Nov 2026 10:17:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=nbmowXKf Received: by smtp.kernel.org (Postfix) with ESMTPSA id B79291F000C1; Tue, 3 Nov 2026 10:17:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793701045; bh=HpuhWfRnhDWwgGiVmFHq8YO9RwBFI28MytzQ8eKOoHg=; h=Subject:To:Cc:From:Date; b=nbmowXKfZIFYiaO5jGSBsPhtLeI7OKq5B/Wggfuu69BOEwBG6zNNO1/pRiU5KCRoA rUPt9vYSXuDoA75t/uRWjJ+GthnJF+L210kvfwBb3h15997Vsh8xWP8qljtNgvp+ps 37fXLPl8ka2G9t+th2TQXSMDu4KPZF/WdDL2xNX0= Subject: FAILED: patch "[PATCH] ksmbd: fix session reference leak on compounded SESSION_SETUP" failed to apply to 6.1-stable tree To: icb@fastmail.org,linkinjeon@kernel.org Cc: From: Date: Tue, 03 Nov 2026 11:17:20 +0100 Message-ID: <2026110320-denture-coke-1c72@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 03bd8f5279e490e15e0c0f0fa388ffbd2fbacd65 # git commit -s git send-email --to '' --in-reply-to '2026110320-denture-coke-1c72@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 03bd8f5279e490e15e0c0f0fa388ffbd2fbacd65 Mon Sep 17 00:00:00 2001 From: Ian Bridges Date: Tue, 27 Oct 2026 10:21:35 -0500 Subject: [PATCH] ksmbd: fix session reference leak on compounded SESSION_SETUP A compound request can place SESSION_SETUP after another command. That earlier command leaves a reference to its session in work->sess. smb2_sess_setup() then overwrites work->sess with the session it looks up or creates, and the dispatcher later puts work->sess only once. The inherited reference is never dropped. That leaks the session, together with its setup connection and socket, and every repeat of the compound leaks another. unreferenced object (size 512): __kmalloc_cache_noprof+0x32c/0x3a0 ksmbd_smb2_session_create+0xf6/0x9c0 [ksmbd] smb2_sess_setup+0xda4/0x6280 [ksmbd] handle_ksmbd_work+0x88c/0x1cb0 [ksmbd] Save the inherited session on entry. After the request has been processed, release it once, but only when smb2_sess_setup() has replaced work->sess with its own session or cleared it. Do this after ksmbd_conn_unlock() so the put does not run under srv_mutex. An error path may instead leave the inherited session in work->sess. Keep it there, so the dispatcher still puts it and the error response is still signed or encrypted with it as before. Fixes: 7aa8804c0b67 ("ksmbd: fix user-after-free from session log off") Cc: stable@vger.kernel.org Signed-off-by: Ian Bridges Signed-off-by: Namjae Jeon diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index f4b61521beac..9f2b435fd437 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2563,6 +2563,8 @@ int smb2_sess_setup(struct ksmbd_work *work) struct smb2_sess_setup_req *req; struct smb2_sess_setup_rsp *rsp; struct ksmbd_session *sess = NULL; + struct ksmbd_session *prev_sess = work->sess; + bool installed = false; struct negotiate_message *negblob; unsigned int negblob_len, negblob_off; u64 previous_session_id = 0; @@ -2679,6 +2681,7 @@ int smb2_sess_setup(struct ksmbd_work *work) int sign_ret; work->sess = sess; + installed = true; if (sess->dialect >= SMB30_PROT_ID) sign_ret = smb3_check_sign_req(work); else @@ -2731,6 +2734,7 @@ int smb2_sess_setup(struct ksmbd_work *work) conn->binding = false; } work->sess = sess; + installed = true; negblob_off = le16_to_cpu(req->SecurityBufferOffset); negblob_len = le16_to_cpu(req->SecurityBufferLength); @@ -2928,6 +2932,14 @@ int smb2_sess_setup(struct ksmbd_work *work) } ksmbd_conn_unlock(conn); + + /* + * Later in a compound, work->sess holds the reference that an + * earlier command took. Drop it once this request has installed + * its own session there or cleared it. + */ + if (prev_sess && (installed || !work->sess)) + ksmbd_user_session_put(prev_sess); return rc; }