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 0074B3B9617 for ; Mon, 31 Aug 2026 22:20:12 +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=1788214814; cv=none; b=kglH8dT0uGOgmzQx7c82ZgffnaWLuFVQZQWpw+AUB3z40U5ONkSgCzEaEKXYXsZU9JMvRxy8EJloRWqXdEW8PYBFWHBZg6cfkjuGRkwCNhAxR/pQ6uDCOgQ+ei2sTaiaFZgLI/cYf+XutHQGLBC/TlTSf+Fp++OKQHwvLWD7O0s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788214814; c=relaxed/simple; bh=li68G3PbT7ZQJPWQBNDHTwUb57hT4uf0csZYv85crD4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eDsG63+ndU/bi6xej+g+x/6EAGqMM4wnKUsf8uqojbITl92rmyCJPe+JxUmsPmXR9w091PbHIi/6Vh8AYipxt1S4NBjnm4iEd29moqIjZ+SMOtmiqTKdJkaQXdLbugDt4d8WGkTtusu3VLBywLc6qhgBU1wTzDWo3sc0FGMFwRw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MRtshlH1; 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="MRtshlH1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C059D1F00A3E; Mon, 31 Aug 2026 22:20:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788214812; bh=lXOmH3kz9v2zmrhwqlaPCD8n43nYMEVRXenroHOLrlE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MRtshlH187DeXhhJedMhRBsLYjzQhO75jpDPCaTpUWB1A/riIdtUc5zs83K6CiR8t 3vG2HHHrTIpQAvKLd7Dlt+nsbz1fIgDWMVg0l+XPVQTVR7Loc0Qewx6aRfYvI8sq2D 3MROCns2HCEho47hr3U3aWl2EY+pbwPuPnMc3/FoQsGvtVG1hiHm+E0rJ3GSbnqy+y XSlDzBixo5LYBvvOBAxBpquLhTmA3bA728k/aXzmUejLH4K1USs4aoPCL4Tdz7v7+o LW3h1iecSfayfl6qy1gzDfU8qTuCqjs5o0kMvEfHvfJ2i/Vk4iZS+MnSBQTNbhxYv7 HQCX5BnDcJFqg== From: Sasha Levin To: stable@vger.kernel.org Cc: Xiang Mei , Weiming Shi , Bernd Schubert , Joanne Koong , Miklos Szeredi , Sasha Levin Subject: [PATCH 6.18.y 6/6] fuse: copy request headers via a stack buffer for io-uring Date: Mon, 31 Aug 2026 18:20:04 -0400 Message-ID: <20260831222004.1858878-6-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260831222004.1858878-1-sashal@kernel.org> References: <2026083142-defile-crewmate-74f2@gregkh> <20260831222004.1858878-1-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: Xiang Mei [ Upstream commit fd10f40af314f07b6d6e028b1ca25c8b49903aab ] 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 [ merged declaration of `in_header`/`out_header` alongside pre-existing `ring`/`fc` locals introduced by prior refactors ] Signed-off-by: Sasha Levin --- fs/fuse/dev_uring.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c index 95c23c3499e78..fc84ef09a164b 100644 --- a/fs/fuse/dev_uring.c +++ b/fs/fuse/dev_uring.c @@ -745,6 +745,7 @@ static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent, { struct fuse_ring_queue *queue = ent->queue; struct fuse_ring *ring = queue->ring; + struct fuse_in_header in_header; int err; err = -EIO; @@ -766,8 +767,9 @@ 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 int fuse_uring_prepare_send(struct fuse_ring_ent *ent, @@ -901,11 +903,13 @@ static void fuse_uring_commit(struct fuse_ring_ent *ent, struct fuse_req *req, { struct fuse_ring *ring = ent->queue->ring; struct fuse_conn *fc = ring->fc; + 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, fc); if (err) { -- 2.53.0