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=1792594273; b=eQnYtj9pkOE/MIYVsIP3c9iaIolnDYMfGNc6ag/aASsHr0o+BVyrzNdBY/UoEVqrpEzK uICyOzwqiZG920NCrehrva8feaI2Qk+f/xLD927XDhTTVzODMVMc0OpBMGgK0VZ30ZKIM 8eYt0aSRs/EIddW/PY5PYIk6NLYJmo0jhWmX7vpJrN1bdZEozufJfDOrKytJNLtIE+fkC 5ItUu+Qe9TVsXCEgaiJ4kqfggVGdSpsH+T8r5JsOhCM4A3OcWf0PK/wFgnaUPj1jcn/kx DhBaFzxValoY8TCWWnRtYzJkpYCEQ538ACdGBhnsvlgVmk0oggmf7tpkrsxrhLWdeSA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792594273; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=F7z0C7tlNJ0D++4CRQnSig3A3Rxva8KLb8gbKwL7mt0=; b=ict/oWY8+HVSvRmsICLNc2DR735JzmeWzCf8y4oeEeYTb7lxJ6QNKM/eTG8DViY4kZ7v 35cNOEyTWVL/RSoEy9KWcTDnHt29Pa9cosXQmHPb7yMqUUneoT4KPDnvke8+20NYTHGus QVWDJ1Q9L3kPjZ3+B6ZJUL6UmIxKPHjG+4xvnArl0+7OU0hGVWjX379qzS3fPgaaHR2aw x+lp9L6Gby0PFCgXHgAyiSJP+tRdrq7HB2lfqzNIIagt4SzKWEUg8xh74fG9D1YdkR0jR 7NCQOp6SNo+vkIt7zwL8yqPZQasmMczDy1lkdZPqT3oCow4DShhfolPUsfxZBguva9w== 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=2r0h3NhR; 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 1C5D4606A323 for ; Wed, 21 Oct 2026 14:51:13 +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=2r0h3NhR Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F9D11F000C3; Wed, 21 Oct 2026 14:51:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792594273; bh=F7z0C7tlNJ0D++4CRQnSig3A3Rxva8KLb8gbKwL7mt0=; h=Subject:To:Cc:From:Date; b=2r0h3NhRR76LheyyniSP3aGq/Qc367r6e9rShcokMGbPSHCPDxvYK5atHo3mhKway 5yNXkNmYD4Gw4trqpFde2QVfOXQ/MKu7vArKoYcY38W9Jh6jfqsylJdfXQsPeM3K5U /L1tV0H189RJNZz5iiYKvIfGQpsm8Be+NRAR+47Q= Subject: FAILED: patch "[PATCH] scsi: st: Fix use-after-free race between st_remove() and" failed to apply to 6.18-stable tree To: loberman@redhat.com,dingiso.kernel@gmail.com,mkp@kernel.org Cc: From: Date: Wed, 21 Oct 2026 16:44:28 +0200 Message-ID: <2026102128-conjoined-uncoiled-3c92@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 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x 71caf7f84bd62a4bf91cc95abd2de690afb8d15f # git commit -s git send-email --to '' --in-reply-to '2026102128-conjoined-uncoiled-3c92@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 71caf7f84bd62a4bf91cc95abd2de690afb8d15f Mon Sep 17 00:00:00 2001 From: Laurence Oberman Date: Tue, 13 Oct 2026 16:25:48 -0400 Subject: [PATCH] scsi: st: Fix use-after-free race between st_remove() and st_open() st_remove() drops the probe reference on the scsi_tape with kref_put() and only afterwards removes its index from st_index_idr. If that was the last reference, scsi_tape_release() frees the structure while it is still published in the idr. scsi_tape_get(), called from st_open(), looks up the tape in st_index_idr and takes a reference under st_ref_mutex and st_index_lock. remove_cdevs() does not wait for opens that are already past chrdev_open(), so an open that is blocked on st_ref_mutex while st_remove() holds it can take the mutex as soon as st_remove() drops it, find the freed tpnt in the idr and call kref_get() on it: BUG: KASAN: slab-use-after-free in st_open Write of size 4 ... st_open (drivers/scsi/st.c:254 drivers/scsi/st.c:1291) chrdev_open ... Freed by task ...: kfree st_remove (drivers/scsi/st.c:4512) Remove the index from the idr before dropping the reference, all under st_ref_mutex. A concurrent scsi_tape_get() now either runs first and holds a valid reference that keeps the tape alive, or runs afterwards and finds nothing, so st_open() fails with -ENXIO. This restores the ordering st_remove() had before the conversion to st_index_idr, where the tape was unpublished from scsi_tapes[] before the final kref_put(). Fixes: 6c648d95a6af ("[SCSI] st: get rid of scsi_tapes array") Cc: stable@vger.kernel.org Reported-by: Dingisoul Closes: https://lore.kernel.org/linux-scsi/20261007211520.1428497-1-dingiso.kernel@gmail.com/ Tested-by: Dingisoul Signed-off-by: Laurence Oberman Link: https://patch.msgid.link/20261013202548.249628-1-loberman@redhat.com Signed-off-by: Martin K. Petersen (Oracle) diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c index cab8aa73969c..a757646c8dc6 100644 --- a/drivers/scsi/st.c +++ b/drivers/scsi/st.c @@ -4515,11 +4515,11 @@ static void st_remove(struct scsi_device *SDp) remove_cdevs(tpnt); mutex_lock(&st_ref_mutex); - kref_put(&tpnt->kref, scsi_tape_release); - mutex_unlock(&st_ref_mutex); spin_lock(&st_index_lock); idr_remove(&st_index_idr, index); spin_unlock(&st_index_lock); + kref_put(&tpnt->kref, scsi_tape_release); + mutex_unlock(&st_ref_mutex); } /**