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 --- fs/sysfs/Kconfig | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 fs/sysfs/Kconfig (limited to 'fs/sysfs/Kconfig') diff --git a/fs/sysfs/Kconfig b/fs/sysfs/Kconfig new file mode 100644 index 000000000..b0fe1cce3 --- /dev/null +++ b/fs/sysfs/Kconfig @@ -0,0 +1,25 @@ +# SPDX-License-Identifier: GPL-2.0-only +config SYSFS + bool "sysfs file system support" if EXPERT + default y + select KERNFS + help + The sysfs filesystem is a virtual filesystem that the kernel uses to + export internal kernel objects, their attributes, and their + relationships to one another. + + Users can use sysfs to ascertain useful information about the running + kernel, such as the devices the kernel has discovered on each bus and + which driver each is bound to. sysfs can also be used to tune devices + and other kernel subsystems. + + Some system agents rely on the information in sysfs to operate. + /sbin/hotplug uses device and object attributes in sysfs to assist in + delegating policy decisions, like persistently naming devices. + + sysfs is currently used by the block subsystem to mount the root + partition. If sysfs is disabled you must specify the boot device on + the kernel boot command line via its major and minor numbers. For + example, "root=03:01" for /dev/hda1. + + Designers of embedded systems may wish to say N here to conserve space. -- cgit v1.3.1