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 --- samples/livepatch/livepatch-callbacks-mod.c | 42 +++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 samples/livepatch/livepatch-callbacks-mod.c (limited to 'samples/livepatch/livepatch-callbacks-mod.c') diff --git a/samples/livepatch/livepatch-callbacks-mod.c b/samples/livepatch/livepatch-callbacks-mod.c new file mode 100644 index 000000000..d1851b471 --- /dev/null +++ b/samples/livepatch/livepatch-callbacks-mod.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Joe Lawrence + */ + +/* + * livepatch-callbacks-mod.c - (un)patching callbacks demo support module + * + * + * Purpose + * ------- + * + * Simple module to demonstrate livepatch (un)patching callbacks. + * + * + * Usage + * ----- + * + * This module is not intended to be standalone. See the "Usage" + * section of livepatch-callbacks-demo.c. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include + +static int livepatch_callbacks_mod_init(void) +{ + pr_info("%s\n", __func__); + return 0; +} + +static void livepatch_callbacks_mod_exit(void) +{ + pr_info("%s\n", __func__); +} + +module_init(livepatch_callbacks_mod_init); +module_exit(livepatch_callbacks_mod_exit); +MODULE_DESCRIPTION("Live patching demo for (un)patching callbacks, support module"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1