From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- drivers/rtc/nvmem.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 drivers/rtc/nvmem.c (limited to 'drivers/rtc/nvmem.c') diff --git a/drivers/rtc/nvmem.c b/drivers/rtc/nvmem.c new file mode 100644 index 000000000..37df7e805 --- /dev/null +++ b/drivers/rtc/nvmem.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * RTC subsystem, nvmem interface + * + * Copyright (C) 2017 Alexandre Belloni + */ + +#include +#include +#include +#include + +int devm_rtc_nvmem_register(struct rtc_device *rtc, + struct nvmem_config *nvmem_config) +{ + struct device *dev = rtc->dev.parent; + struct nvmem_device *nvmem; + + if (!nvmem_config) + return -ENODEV; + + nvmem_config->dev = dev; + nvmem_config->owner = rtc->owner; + nvmem_config->add_legacy_fixed_of_cells = true; + nvmem = devm_nvmem_register(dev, nvmem_config); + if (IS_ERR(nvmem)) + dev_err(dev, "failed to register nvmem device for RTC\n"); + + return PTR_ERR_OR_ZERO(nvmem); +} +EXPORT_SYMBOL_GPL(devm_rtc_nvmem_register); -- cgit v1.3.1