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 --- lib/842/842_debugfs.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 lib/842/842_debugfs.h (limited to 'lib/842/842_debugfs.h') diff --git a/lib/842/842_debugfs.h b/lib/842/842_debugfs.h new file mode 100644 index 000000000..4469407c3 --- /dev/null +++ b/lib/842/842_debugfs.h @@ -0,0 +1,50 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __842_DEBUGFS_H__ +#define __842_DEBUGFS_H__ + +#include + +static bool sw842_template_counts; +module_param_named(template_counts, sw842_template_counts, bool, 0444); + +static atomic_t template_count[OPS_MAX], template_repeat_count, + template_zeros_count, template_short_data_count, template_end_count; + +static struct dentry *sw842_debugfs_root; + +static int __init sw842_debugfs_create(void) +{ + umode_t m = S_IRUGO | S_IWUSR; + int i; + + if (!debugfs_initialized()) + return -ENODEV; + + sw842_debugfs_root = debugfs_create_dir(MODULE_NAME, NULL); + + for (i = 0; i < ARRAY_SIZE(template_count); i++) { + char name[32]; + + snprintf(name, 32, "template_%02x", i); + debugfs_create_atomic_t(name, m, sw842_debugfs_root, + &template_count[i]); + } + debugfs_create_atomic_t("template_repeat", m, sw842_debugfs_root, + &template_repeat_count); + debugfs_create_atomic_t("template_zeros", m, sw842_debugfs_root, + &template_zeros_count); + debugfs_create_atomic_t("template_short_data", m, sw842_debugfs_root, + &template_short_data_count); + debugfs_create_atomic_t("template_end", m, sw842_debugfs_root, + &template_end_count); + + return 0; +} + +static void __exit sw842_debugfs_remove(void) +{ + debugfs_remove_recursive(sw842_debugfs_root); +} + +#endif -- cgit v1.3.1