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/dca/dca-sysfs.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 drivers/dca/dca-sysfs.c (limited to 'drivers/dca/dca-sysfs.c') diff --git a/drivers/dca/dca-sysfs.c b/drivers/dca/dca-sysfs.c new file mode 100644 index 000000000..b915c2b46 --- /dev/null +++ b/drivers/dca/dca-sysfs.c @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright(c) 2007 - 2009 Intel Corporation. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static const struct class dca_class = { + .name = "dca", +}; +static struct idr dca_idr; +static spinlock_t dca_idr_lock; + +int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot) +{ + struct device *cd; + static int req_count; + + cd = device_create(&dca_class, dca->cd, MKDEV(0, slot + 1), NULL, + "requester%d", req_count++); + return PTR_ERR_OR_ZERO(cd); +} + +void dca_sysfs_remove_req(struct dca_provider *dca, int slot) +{ + device_destroy(&dca_class, MKDEV(0, slot + 1)); +} + +int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev) +{ + struct device *cd; + int ret; + + idr_preload(GFP_KERNEL); + spin_lock(&dca_idr_lock); + + ret = idr_alloc(&dca_idr, dca, 0, 0, GFP_NOWAIT); + if (ret >= 0) + dca->id = ret; + + spin_unlock(&dca_idr_lock); + idr_preload_end(); + if (ret < 0) + return ret; + + cd = device_create(&dca_class, dev, MKDEV(0, 0), NULL, "dca%d", dca->id); + if (IS_ERR(cd)) { + spin_lock(&dca_idr_lock); + idr_remove(&dca_idr, dca->id); + spin_unlock(&dca_idr_lock); + return PTR_ERR(cd); + } + dca->cd = cd; + return 0; +} + +void dca_sysfs_remove_provider(struct dca_provider *dca) +{ + device_unregister(dca->cd); + dca->cd = NULL; + spin_lock(&dca_idr_lock); + idr_remove(&dca_idr, dca->id); + spin_unlock(&dca_idr_lock); +} + +int __init dca_sysfs_init(void) +{ + int err; + + idr_init(&dca_idr); + spin_lock_init(&dca_idr_lock); + + err = class_register(&dca_class); + if (err) { + idr_destroy(&dca_idr); + return err; + } + return 0; +} + +void __exit dca_sysfs_exit(void) +{ + class_unregister(&dca_class); + idr_destroy(&dca_idr); +} + -- cgit v1.3.1