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 4B9833E6386 for ; Mon, 31 Aug 2026 12:23:56 +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=1788179037; cv=none; b=iPRfUXrNSFTsapc7TKoyqyPXZYg8RWS78APfyTl5O94+tTPBOZYXC8QmiOTF6hK3YZbn5Zkpsy20Yp6RcmnShFS821oa15z8zNa22BeZ4xxtgbMrltwkfkrSzljf7aOv0zUH7HnH1KSz8RCMJarKipyctYSYSC1AWSmPCpqD8tA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788179037; c=relaxed/simple; bh=Tvk6/ugfclbj827FEl5niTdYKUE/IKqLYAoZtowH0u8=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=ENIU3ToF6lUP14WfrHYJ72vPd80hn8MWnMEonmaY1Dd1tX8JzgxvPDxzP5yjGKcC64bjp6HipRwFbBg5QAtAzFNRXqNQy+kTl3jCmlfjyjtcw/JS6ihibb5x8U32tqJZQIKKeX008TDIcTGp0hV58x/wJF6+9Ihn38WZ+h9V7Eg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ABgmEUoN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ABgmEUoN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A55BD1F000E9; Mon, 31 Aug 2026 12:23:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788179036; bh=sOb6ZEechDAnXkGhkrBZ3qBvZd+cI+lfUxQKGOSYXsM=; h=Subject:To:Cc:From:Date; b=ABgmEUoN5r5GPuJoTk8AHxpS5aFxYLfw5a88LR8VCkUXbnOEtjDRPNc8K/HdIebjA j5k1EozFmQdXIDZAKR4qJmNsedONHFdbGDohu81gA2M8uB1x5sbYxwi0H6MXRUxZp8 LXosxBZK2Y75HTbkWnz9wDXZV2E5ai6s5D6Qc4Qg= Subject: FAILED: patch "[PATCH] fuse: copy request headers via a stack buffer for io-uring" failed to apply to 6.18-stable tree To: xmei5@asu.edu,bernd@bsbernd.com,bestswngs@gmail.com,joannelkoong@gmail.com,mszeredi@redhat.com Cc: From: Date: Mon, 31 Aug 2026 14:23:42 +0200 Message-ID: <2026083142-defile-crewmate-74f2@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 fd10f40af314f07b6d6e028b1ca25c8b49903aab # git commit -s git send-email --to '' --in-reply-to '2026083142-defile-crewmate-74f2@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From fd10f40af314f07b6d6e028b1ca25c8b49903aab Mon Sep 17 00:00:00 2001 From: Xiang Mei Date: Mon, 27 Jul 2026 16:37:04 -0700 Subject: [PATCH] fuse: copy request headers via a stack buffer for io-uring The fuse-io-uring transport copies req->in.h out to the ring in fuse_uring_copy_to_ring() and req->out.h back in fuse_uring_commit(). Both headers live inside the fuse_request slab object, whose cache (fuse_req_cachep) is created without a usercopy whitelist, so copying them directly to/from userspace trips CONFIG_HARDENED_USERCOPY and panics: usercopy: Kernel memory exposure attempt detected from SLUB object 'fuse_request' (offset 56, size 40)! kernel BUG at mm/usercopy.c:102! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:usercopy_abort (mm/usercopy.c:90) Call Trace: __check_heap_object (mm/slub.c:8268) __check_object_size (mm/usercopy.c:197 mm/usercopy.c:258 mm/usercopy.c:223) copy_header_to_ring (fs/fuse/dev_uring.c:618) fuse_uring_prepare_send (fs/fuse/dev_uring.c:776 fs/fuse/dev_uring.c:785) fuse_uring_send_in_task (fs/fuse/dev_uring.c:1306) tctx_task_work_run (io_uring/tw.c:96) task_work_run (kernel/task_work.c:233) io_run_task_work (io_uring/tw.h:84) io_cqring_wait (io_uring/wait.c:278) __do_sys_io_uring_enter (io_uring/io_uring.c:2685) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Bounce both headers through an on-stack copy so the usercopy touches stack memory, not the slab object. Fixes: c090c8abae4b ("fuse: Add io-uring sqe commit and fetch support") Cc: stable@vger.kernel.org Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Xiang Mei Reviewed-by: Bernd Schubert Reviewed-by: Joanne Koong Signed-off-by: Miklos Szeredi diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c index 1547a4f0d9b9..e22a48c9a678 100644 --- a/fs/fuse/dev_uring.c +++ b/fs/fuse/dev_uring.c @@ -922,6 +922,7 @@ static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent, unsigned int issue_flags) { struct fuse_ring_queue *queue = ent->queue; + struct fuse_in_header in_header; int err; err = -EIO; @@ -943,8 +944,9 @@ static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent, } /* copy fuse_in_header */ - return copy_header_to_ring(ent, FUSE_URING_HEADER_IN_OUT, &req->in.h, - sizeof(req->in.h)); + in_header = req->in.h; + return copy_header_to_ring(ent, FUSE_URING_HEADER_IN_OUT, &in_header, + sizeof(in_header)); } static bool fuse_uring_req_has_copyable_payload(struct fuse_ring_ent *ent, @@ -1151,11 +1153,13 @@ static struct fuse_req *fuse_uring_ent_assign_req(struct fuse_ring_ent *ent) static void fuse_uring_commit(struct fuse_ring_ent *ent, struct fuse_req *req, unsigned int issue_flags) { + struct fuse_out_header out_header; ssize_t err = -EFAULT; - if (copy_header_from_ring(ent, FUSE_URING_HEADER_IN_OUT, &req->out.h, - sizeof(req->out.h))) + if (copy_header_from_ring(ent, FUSE_URING_HEADER_IN_OUT, &out_header, + sizeof(out_header))) goto out; + req->out.h = out_header; err = fuse_uring_out_header_has_err(&req->out.h, req); if (err) {