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/trace_printk/Makefile | 7 +++++ samples/trace_printk/trace-printk.c | 58 +++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) create mode 100644 samples/trace_printk/Makefile create mode 100644 samples/trace_printk/trace-printk.c (limited to 'samples/trace_printk') diff --git a/samples/trace_printk/Makefile b/samples/trace_printk/Makefile new file mode 100644 index 000000000..c0df36167 --- /dev/null +++ b/samples/trace_printk/Makefile @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: GPL-2.0-only +# builds a module that calls various trace_printk routines +# then to use one (as root): insmod + +# This module can also be used to test the trace_printk code. + +obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace-printk.o diff --git a/samples/trace_printk/trace-printk.c b/samples/trace_printk/trace-printk.c new file mode 100644 index 000000000..cfc159580 --- /dev/null +++ b/samples/trace_printk/trace-printk.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +/* Must not be static to force gcc to consider these non constant */ +char *trace_printk_test_global_str = + "This is a dynamic string that will use trace_puts\n"; + +char *trace_printk_test_global_str_irq = + "(irq) This is a dynamic string that will use trace_puts\n"; + +char *trace_printk_test_global_str_fmt = + "%sThis is a %s that will use trace_printk\n"; + +static struct irq_work irqwork; + +static void trace_printk_irq_work(struct irq_work *work) +{ + trace_printk("(irq) This is a static string that will use trace_bputs\n"); + trace_printk(trace_printk_test_global_str_irq); + + trace_printk("(irq) This is a %s that will use trace_bprintk()\n", + "static string"); + + trace_printk(trace_printk_test_global_str_fmt, + "(irq) ", "dynamic string"); +} + +static int __init trace_printk_init(void) +{ + init_irq_work(&irqwork, trace_printk_irq_work); + + trace_printk("This is a static string that will use trace_bputs\n"); + trace_printk(trace_printk_test_global_str); + + /* Kick off printing in irq context */ + irq_work_queue(&irqwork); + irq_work_sync(&irqwork); + + trace_printk("This is a %s that will use trace_bprintk()\n", + "static string"); + + trace_printk(trace_printk_test_global_str_fmt, "", "dynamic string"); + + return 0; +} + +static void __exit trace_printk_exit(void) +{ +} + +module_init(trace_printk_init); +module_exit(trace_printk_exit); + +MODULE_AUTHOR("Steven Rostedt"); +MODULE_DESCRIPTION("trace-printk"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1