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 --- arch/powerpc/sysdev/dcr.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 arch/powerpc/sysdev/dcr.c (limited to 'arch/powerpc/sysdev/dcr.c') diff --git a/arch/powerpc/sysdev/dcr.c b/arch/powerpc/sysdev/dcr.c new file mode 100644 index 000000000..cb44a6995 --- /dev/null +++ b/arch/powerpc/sysdev/dcr.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp. + * + */ + +#undef DEBUG + +#include +#include +#include +#include + +unsigned int dcr_resource_start(const struct device_node *np, + unsigned int index) +{ + unsigned int ds; + const u32 *dr = of_get_property(np, "dcr-reg", &ds); + + if (dr == NULL || ds & 1 || index >= (ds / 8)) + return 0; + + return dr[index * 2]; +} +EXPORT_SYMBOL_GPL(dcr_resource_start); + +unsigned int dcr_resource_len(const struct device_node *np, unsigned int index) +{ + unsigned int ds; + const u32 *dr = of_get_property(np, "dcr-reg", &ds); + + if (dr == NULL || ds & 1 || index >= (ds / 8)) + return 0; + + return dr[index * 2 + 1]; +} +EXPORT_SYMBOL_GPL(dcr_resource_len); + +DEFINE_SPINLOCK(dcr_ind_lock); +EXPORT_SYMBOL_GPL(dcr_ind_lock); -- cgit v1.3.1