From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F3AB170838; Thu, 6 Mar 2025 14:36:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741271780; cv=none; b=S29zqZYf7Ozq4D1sHAqsa48MTPQ35pRC2Lv+EXI3qesviZMWKj3lzPQEFXqY1vCPrEkw8d1pjB7M08ZLk2o2RYvxi9Id4/Dqyaz4LdS+IpF5exuKFwylQjXAIhn1b674T6ZHoi0IGGOxHfcnTzCnxP7ymJvZbowIYcXBvTOO9T8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741271780; c=relaxed/simple; bh=+hBsYDGnvL3coGgp/aBij1w2/BTz8yx/AQM8HVZKSVg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mTcY5k/c4F0TeHGJF7fXFbbkUS0vVbNGvD8ZEq9bc+kVG9D9kZMY5N2ko0UZIiTAcDwKJAv76jRBUzgNhcytUC/ES4rZKimrKGvDTmFIXTPDibfJGX/mIr6tbZO2/Dt7fYrDgYCxSRkpfw0OcXx4GEIh5OJd3s9/EtT4g5qnny4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7979C4CEE0; Thu, 6 Mar 2025 14:36:18 +0000 (UTC) Date: Thu, 6 Mar 2025 14:36:16 +0000 From: Catalin Marinas To: Alice Ryhl Cc: Cristian Marussi , Sudeep Holla , linux-arm-kernel@lists.infradead.org, arm-scmi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Bug report] Memory leak in scmi_device_create Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Mar 06, 2025 at 11:09:33AM +0000, Alice Ryhl wrote: > On Wed, Mar 05, 2025 at 05:10:16PM +0000, Cristian Marussi wrote: > > On Wed, Mar 05, 2025 at 11:59:58AM +0000, Alice Ryhl wrote: > > > This was with a kernel running v6.13-rc3, but as far as I can tell, no > > > relevant changes have landed since v6.13-rc3. My tree *does* include > > > commit 295416091e44 ("firmware: arm_scmi: Fix slab-use-after-free in > > > scmi_bus_notifier()"). I've only seen this kmemleak report once, so it's > > > not happening consistently. > > > > > > See below for the full kmemleak report. > > > > > > Alice > > > > > > $ sudo cat /sys/kernel/debug/kmemleak > > > unreferenced object 0xffffff8106c86000 (size 2048): > > > comm "swapper/0", pid 1, jiffies 4294893094 > > > hex dump (first 32 bytes): > > > 02 00 00 00 10 00 00 00 c0 01 bc 03 81 ff ff ff ................ > > > 60 67 ba 03 81 ff ff ff 18 60 c8 06 81 ff ff ff `g.......`...... > > > backtrace (crc feae9680): > > > [<00000000197aa008>] kmemleak_alloc+0x34/0xa0 > > > [<0000000056fe02c9>] __kmalloc_cache_noprof+0x1e0/0x450 > > > [<00000000a8b3dfe1>] __scmi_device_create+0xb4/0x2b4 > > > [<000000008714917b>] scmi_device_create+0x40/0x194 > > > [<000000001818f3cf>] scmi_chan_setup+0x144/0x3b8 > > > [<00000000970bad38>] scmi_probe+0x584/0xa78 > > > [<000000002600d2fd>] platform_probe+0xbc/0xf0 > > > [<00000000f6f556b4>] really_probe+0x1b8/0x520 > > > [<00000000eed93d59>] __driver_probe_device+0xe0/0x1d8 > > > [<00000000d613b754>] driver_probe_device+0x6c/0x208 > > > [<00000000187a9170>] __driver_attach+0x168/0x328 > > > [<00000000e3ff1834>] bus_for_each_dev+0x14c/0x178 > > > [<00000000984a3176>] driver_attach+0x34/0x44 > > > [<00000000fc35bf2a>] bus_add_driver+0x1bc/0x358 > > > [<00000000747fce19>] driver_register+0xc0/0x1a0 > > > [<0000000081cb8754>] __platform_driver_register+0x40/0x50 > > > unreferenced object 0xffffff8103bc01c0 (size 32): > > > > I could not reproduce on my setup, even though I run a system with > > all the existent SCMI protocols (and related drivers) enabled (and > > so a lot of device creations) and a downstream test driver that causes > > even more SCMI devices to be created/destroyed at load/unload. > > > > Coming down the path from scmi_chan_setup(), it seems something around > > transport devices creation, but it is not obvious to me where the leak > > could hide.... > > > > ...any particular setup on your side ? ...using LKMs, loading/unloading, > > any usage pattern that could help me reproduce ? > > I looked into this a bit more, and actually it does happen consistently. > It's just that kmemleak doesn't report it until 10 minutes after > booting, so I did not notice it. You can force the scanning with: echo scan > /sys/kernel/debug/kmemleak Just do it a couple of times after boot, no need to wait 10 min for the default background scanning. > user@rk3588-ci:~$ sudo cat /sys/kernel/debug/kmemleak > unreferenced object 0xffffff81068c0000 (size 2048): > comm "swapper/0", pid 1, jiffies 4294893128 > hex dump (first 32 bytes): > 02 00 00 00 10 00 00 00 40 a3 7a 03 81 ff ff ff ........@.z..... > 60 c8 79 03 81 ff ff ff 18 00 8c 06 81 ff ff ff `.y............. > backtrace (crc 60df30fb): > kmemleak_alloc+0x34/0xa0 > __kmalloc_cache_noprof+0x1e0/0x450 > __scmi_device_create+0xb4/0x2b4 Is this the kzalloc() for sizeof(*scmi_dev)? It's surprisingly large, I thought it would go for the kmalloc-1k slab as struct device is below this side, at least for my builds. Anyway... > scmi_device_create+0x40/0x194 > scmi_chan_setup+0x144/0x3b8 > scmi_probe+0x51c/0x9fc > platform_probe+0xbc/0xf0 > really_probe+0x1b8/0x520 > __driver_probe_device+0xe0/0x1d8 > driver_probe_device+0x6c/0x208 > __driver_attach+0x168/0x328 > bus_for_each_dev+0x14c/0x178 > driver_attach+0x34/0x44 > bus_add_driver+0x1bc/0x358 > driver_register+0xc0/0x1a0 > __platform_driver_register+0x40/0x50 > unreferenced object 0xffffff81037aa340 (size 32): > comm "swapper/0", pid 1, jiffies 4294893128 > hex dump (first 32 bytes): > 5f 5f 73 63 6d 69 5f 74 72 61 6e 73 70 6f 72 74 __scmi_transport > 5f 64 65 76 69 63 65 5f 72 78 5f 31 30 00 ff ff _device_rx_10... > backtrace (crc 8dab7ca7): > kmemleak_alloc+0x34/0xa0 > __kmalloc_node_track_caller_noprof+0x234/0x528 > kstrdup+0x48/0x80 > kstrdup_const+0x30/0x3c These are referenced from the main structure above, so they'd be reported as leaks as well. This loop in scmi_device_create() looks strange: list_for_each_entry(rdev, phead, node) { struct scmi_device *sdev; sdev = __scmi_device_create(np, parent, rdev->id_table->protocol_id, rdev->id_table->name); /* Report errors and carry on... */ if (sdev) scmi_dev = sdev; else pr_err("(%s) Failed to create device for protocol 0x%x (%s)\n", of_node_full_name(parent->of_node), rdev->id_table->protocol_id, rdev->id_table->name); } We can override scmi_dev a few times in the loop and lose the previous sdev allocations. Is this intended? -- Catalin