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 --- include/drm/drm_util.h | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 include/drm/drm_util.h (limited to 'include/drm/drm_util.h') diff --git a/include/drm/drm_util.h b/include/drm/drm_util.h new file mode 100644 index 000000000..440199618 --- /dev/null +++ b/include/drm/drm_util.h @@ -0,0 +1,69 @@ +/* + * Internal Header for the Direct Rendering Manager + * + * Copyright 2018 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + */ + +#ifndef _DRM_UTIL_H_ +#define _DRM_UTIL_H_ + +/** + * DOC: drm utils + * + * Macros and inline functions that does not naturally belong in other places + */ + +#include +#include +#include +#include +#include + +/* + * Use EXPORT_SYMBOL_FOR_TESTS_ONLY() for functions that shall + * only be visible for drmselftests. + */ +#if defined(CONFIG_DRM_EXPORT_FOR_TESTS) +#define EXPORT_SYMBOL_FOR_TESTS_ONLY(x) EXPORT_SYMBOL(x) +#else +#define EXPORT_SYMBOL_FOR_TESTS_ONLY(x) +#endif + +/** + * drm_can_sleep - returns true if currently okay to sleep + * + * This function shall not be used in new code. + * The check for running in atomic context may not work - see linux/preempt.h. + * + * FIXME: All users of drm_can_sleep should be removed (see todo.rst) + * + * Returns: + * False if kgdb is active, we are in atomic context or irqs are disabled. + */ +static inline bool drm_can_sleep(void) +{ + if (in_atomic() || in_dbg_master() || irqs_disabled()) + return false; + return true; +} + +#endif -- cgit v1.3.1