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 C4E622749E6 for ; Mon, 31 Aug 2026 18:30:06 +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=1788201008; cv=none; b=isp8b63hkq0zVz6krvo7e3/NJqLr7RXBnd3oXjxj/QVB5fKUQP3Of5Wy9+qPVTm+Fq2l5ROxFn6IWxKjY+HI6yCmmdeho6C7xsUCfVnMYVNfFP2A7neRGUF2KwYAgM0nIp5jRhvAHm8EDSIEI88pbYBslqmDzw67jYcDm7EEosg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788201008; c=relaxed/simple; bh=u1fX0oqetFtO017FD2HfXn+Gl3ycJFvUmME5hZjqCSw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IEB2Wpm4jDh6UMZUjM2YcA81PsweSubEUj47+Q/kmrBI/cZp9+HlRuqsNhwO6GPWS7Dps2UMnS6I1VNsR6eeRiE3DpFviRA+78qkcX4hsRSdUzSodB/yzkJcbqN3obASVxveGv7pRJHwBIA2p6rYL7MaJpCsxJKYSYkfJ7rT704= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DFHLhMMr; 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="DFHLhMMr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B05591F00A3E; Mon, 31 Aug 2026 18:30:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788201006; bh=d1B/gtj24I9k5prQbH3cbo0Vy1bDv4+1L2Uq188orpk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DFHLhMMrWaG66Ns26cBoRHKqQrC3SQUlv2dsgghZLjj4Ogj6+Zz2Sy67ga42Rn4Cj pOWZukBTVgK5ZeJRm0LHh4gcBO0a1chPJmhWbCg/rojXQ4tN1CgzQgqAHsj0BPV9Hg lBjBzPAHZmXsnTmUnDw8vNLkYX3heDgVN0jVlSFb6yJNjswpzBLEKcTQCtaX84S4MP iCsBSPiZv96H9jNuD5VcILC7kRcMEo2Thq57aJkcBkFvBkMALrwQk6Ob1JThuxh7j5 AnThnC6UNGYpJeaY3YujxoscZrP9BG8hQQkDtq5RA3hvq58D8tk1sAw+b1vLEoAiXk tuof33FvCXmOg== From: Sasha Levin To: stable@vger.kernel.org Cc: Xiang Mei , Weiming Shi , Bernd Schubert , Joanne Koong , Miklos Szeredi , Sasha Levin Subject: [PATCH 7.2.y 2/2] fuse: copy request headers via a stack buffer for io-uring Date: Mon, 31 Aug 2026 14:30:02 -0400 Message-ID: <20260831183002.1670211-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260831183002.1670211-1-sashal@kernel.org> References: <2026083141-juicy-elated-cee2@gregkh> <20260831183002.1670211-1-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 [ adapted context due to a pre-existing local `ring` local variable from an earlier already-backported commit shifting line numbers ] 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 55e0ecdb20582..c4ec7a97a4746 100644 --- a/fs/fuse/dev_uring.c +++ b/fs/fuse/dev_uring.c @@ -743,6 +743,7 @@ 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; @@ -764,8 +765,9 @@ 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, @@ -870,11 +872,13 @@ static void fuse_uring_commit(struct fuse_ring_ent *ent, struct fuse_req *req, unsigned int issue_flags) { struct fuse_ring *ring = ent->queue->ring; + 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) { -- 2.53.0