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/pps/clients/pps-ktimer.c | 87 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 drivers/pps/clients/pps-ktimer.c (limited to 'drivers/pps/clients/pps-ktimer.c') diff --git a/drivers/pps/clients/pps-ktimer.c b/drivers/pps/clients/pps-ktimer.c new file mode 100644 index 000000000..121bd29d8 --- /dev/null +++ b/drivers/pps/clients/pps-ktimer.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * pps-ktimer.c -- kernel timer test client + * + * Copyright (C) 2005-2006 Rodolfo Giometti + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include + +/* + * Global variables + */ + +static struct pps_device *pps; +static struct timer_list ktimer; + +/* + * The kernel timer + */ + +static void pps_ktimer_event(struct timer_list *unused) +{ + struct pps_event_time ts; + + /* First of all we get the time stamp... */ + pps_get_ts(&ts); + + pps_event(pps, &ts, PPS_CAPTUREASSERT, NULL); + + mod_timer(&ktimer, jiffies + HZ); +} + +/* + * The PPS info struct + */ + +static struct pps_source_info pps_ktimer_info = { + .name = "ktimer", + .path = "", + .mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT | + PPS_ECHOASSERT | + PPS_CANWAIT | PPS_TSFMT_TSPEC, + .owner = THIS_MODULE, +}; + +/* + * Module staff + */ + +static void __exit pps_ktimer_exit(void) +{ + dev_dbg(&pps->dev, "ktimer PPS source unregistered\n"); + + timer_delete_sync(&ktimer); + pps_unregister_source(pps); +} + +static int __init pps_ktimer_init(void) +{ + pps = pps_register_source(&pps_ktimer_info, + PPS_CAPTUREASSERT | PPS_OFFSETASSERT); + if (IS_ERR(pps)) { + pr_err("cannot register PPS source\n"); + return PTR_ERR(pps); + } + + timer_setup(&ktimer, pps_ktimer_event, 0); + mod_timer(&ktimer, jiffies + HZ); + + dev_dbg(&pps->dev, "ktimer PPS source registered\n"); + + return 0; +} + +module_init(pps_ktimer_init); +module_exit(pps_ktimer_exit); + +MODULE_AUTHOR("Rodolfo Giometti "); +MODULE_DESCRIPTION("dummy PPS source by using a kernel timer (just for debug)"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1