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/base/auxiliary_sysfs.c | 113 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 drivers/base/auxiliary_sysfs.c (limited to 'drivers/base/auxiliary_sysfs.c') diff --git a/drivers/base/auxiliary_sysfs.c b/drivers/base/auxiliary_sysfs.c new file mode 100644 index 000000000..dea7f46f7 --- /dev/null +++ b/drivers/base/auxiliary_sysfs.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2024, NVIDIA CORPORATION & AFFILIATES + */ + +#include +#include + +#define AUXILIARY_MAX_IRQ_NAME 11 + +struct auxiliary_irq_info { + struct device_attribute sysfs_attr; + char name[AUXILIARY_MAX_IRQ_NAME]; +}; + +static struct attribute *auxiliary_irq_attrs[] = { + NULL +}; + +static const struct attribute_group auxiliary_irqs_group = { + .name = "irqs", + .attrs = auxiliary_irq_attrs, +}; + +static int auxiliary_irq_dir_prepare(struct auxiliary_device *auxdev) +{ + int ret = 0; + + guard(mutex)(&auxdev->sysfs.lock); + if (auxdev->sysfs.irq_dir_exists) + return 0; + + ret = devm_device_add_group(&auxdev->dev, &auxiliary_irqs_group); + if (ret) + return ret; + + auxdev->sysfs.irq_dir_exists = true; + xa_init(&auxdev->sysfs.irqs); + return 0; +} + +/** + * auxiliary_device_sysfs_irq_add - add a sysfs entry for the given IRQ + * @auxdev: auxiliary bus device to add the sysfs entry. + * @irq: The associated interrupt number. + * + * This function should be called after auxiliary device have successfully + * received the irq. + * The driver is responsible to add a unique irq for the auxiliary device. The + * driver can invoke this function from multiple thread context safely for + * unique irqs of the auxiliary devices. The driver must not invoke this API + * multiple times if the irq is already added previously. + * + * Return: zero on success or an error code on failure. + */ +int auxiliary_device_sysfs_irq_add(struct auxiliary_device *auxdev, int irq) +{ + struct auxiliary_irq_info *info __free(kfree) = NULL; + struct device *dev = &auxdev->dev; + int ret; + + ret = auxiliary_irq_dir_prepare(auxdev); + if (ret) + return ret; + + info = kzalloc_obj(*info); + if (!info) + return -ENOMEM; + + sysfs_attr_init(&info->sysfs_attr.attr); + snprintf(info->name, AUXILIARY_MAX_IRQ_NAME, "%d", irq); + + ret = xa_insert(&auxdev->sysfs.irqs, irq, info, GFP_KERNEL); + if (ret) + return ret; + + info->sysfs_attr.attr.name = info->name; + ret = sysfs_add_file_to_group(&dev->kobj, &info->sysfs_attr.attr, + auxiliary_irqs_group.name); + if (ret) + goto sysfs_add_err; + + xa_store(&auxdev->sysfs.irqs, irq, no_free_ptr(info), GFP_KERNEL); + return 0; + +sysfs_add_err: + xa_erase(&auxdev->sysfs.irqs, irq); + return ret; +} +EXPORT_SYMBOL_GPL(auxiliary_device_sysfs_irq_add); + +/** + * auxiliary_device_sysfs_irq_remove - remove a sysfs entry for the given IRQ + * @auxdev: auxiliary bus device to add the sysfs entry. + * @irq: the IRQ to remove. + * + * This function should be called to remove an IRQ sysfs entry. + * The driver must invoke this API when IRQ is released by the device. + */ +void auxiliary_device_sysfs_irq_remove(struct auxiliary_device *auxdev, int irq) +{ + struct auxiliary_irq_info *info __free(kfree) = xa_load(&auxdev->sysfs.irqs, irq); + struct device *dev = &auxdev->dev; + + if (!info) { + dev_err(&auxdev->dev, "IRQ %d doesn't exist\n", irq); + return; + } + sysfs_remove_file_from_group(&dev->kobj, &info->sysfs_attr.attr, + auxiliary_irqs_group.name); + xa_erase(&auxdev->sysfs.irqs, irq); +} +EXPORT_SYMBOL_GPL(auxiliary_device_sysfs_irq_remove); -- cgit v1.3.1