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AJvYcCUspOyAsOwscoeB2LRP940wNenNNYHN4x9OE75Le5slx5FpbqvnykomSyJwVuTPMrFUshbcZErMOgzm95Y=@vger.kernel.org X-Gm-Message-State: AOJu0YwwRy3Nlndk1bnn4ur1XErp2YabgRichX7YOvQHOE/g/qJnAFzq LA5OUlquMMqJAZiLJuaMvT40kjD0yJME70WzRX7Lb95q/ag/AA+JUTPYEcZfEMNvFyr2HF3X1Dd EJpOeCZ1N3RsXOg== X-Google-Smtp-Source: AGHT+IGu6TNRJ9xsT+tbNha9i/40T4DWFVb5ajxHxFzrjaRSighLgqQn9S9T5+RQz5NbxV86JeMfKntspt/d6/4= X-Received: from wmrn30.prod.google.com ([2002:a05:600c:501e:b0:43b:d157:3b9e]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:4447:b0:43b:c0fa:f9e4 with SMTP id 5b1f17b1804b1-43bd29589fcmr52982055e9.13.1741267527969; Thu, 06 Mar 2025 05:25:27 -0800 (PST) Date: Thu, 6 Mar 2025 13:25:25 +0000 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: Message-ID: Subject: Re: [Bug report] Memory leak in scmi_device_create From: Alice Ryhl To: Cristian Marussi Cc: Sudeep Holla , linux-arm-kernel@lists.infradead.org, arm-scmi@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" On Thu, Mar 06, 2025 at 12:50:17PM +0000, Cristian Marussi wrote: > 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: > > > > Dear SYSTEM CONTROL & POWER/MANAGEMENT INTERFACE (SCPI/SCMI) Message > > > > Protocol drivers maintainers, > > > > > > > > I flashed a v6.13-rc3 kernel onto a Rock5B board and noticed the > > > > following output in my terminal: > > > > > > > > [ 687.694465] kmemleak: 4 new suspected memory leaks (see /sys/kernel/debug/kmemleak) > > > > > > > > It seems that there is a memory leak for devices created with > > > > scmi_device_create. > > > > > > > ` > > > Hi Alice, > > > > > > thanks for this report. > > > > > > > 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. > > > > As for my setup, well, I boot the kernel over pxe and the rootfs is > > mounted over NFSv4. The memory leak happens even if I don't do anything > > at all - I just boot and wait. The device is a Radxa Rock5B. > > > > Not sure what other information there is to give. > > > > My question as stated above was mainly to understand if the SCMI stack > was built-in or compiled as loadable modules (lsmod|grep -i scmi)... > ...I am just to try to pin down a possible 'more-vulnerable' configuration.. > ..I could not see any report even triggering a kmemleak scan on v6.14-rc5 > BUT I only tested with a fully built-in SCMI stack indeed as of now...so > the question. > > > I tried again with v6.14-rc5, and I still got the leak: > > Ok...thanks I will investigate with different configs. Here is the config I used: https://gist.github.com/Darksonn/ecd31a0512f43f7e74a30ab83ff2196f Alice