dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel()grafted

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 <sashiko-bot@kernel.org>
Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>
Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 102 insertions, 0 deletions

diff --git a/crypto/fips.c b/crypto/fips.c
new file mode 100644
index 000000000..c59711248
--- /dev/null
+++ b/crypto/fips.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * FIPS 200 support.
+ *
+ * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
+ */
+
+#include <linux/export.h>
+#include <linux/fips.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sysctl.h>
+#include <linux/notifier.h>
+#include <linux/string_choices.h>
+#include <generated/utsrelease.h>
+
+int fips_enabled;
+EXPORT_SYMBOL_GPL(fips_enabled);
+
+ATOMIC_NOTIFIER_HEAD(fips_fail_notif_chain);
+EXPORT_SYMBOL_GPL(fips_fail_notif_chain);
+
+/* Process kernel command-line parameter at boot time. fips=0 or fips=1 */
+static int __init fips_enable(char *str)
+{
+	if (kstrtoint(str, 0, &fips_enabled))
+		return 0;
+
+	fips_enabled = !!fips_enabled;
+	pr_info("fips mode: %s\n", str_enabled_disabled(fips_enabled));
+	return 1;
+}
+
+__setup("fips=", fips_enable);
+
+#define FIPS_MODULE_NAME CONFIG_CRYPTO_FIPS_NAME
+#ifdef CONFIG_CRYPTO_FIPS_CUSTOM_VERSION
+#define FIPS_MODULE_VERSION CONFIG_CRYPTO_FIPS_VERSION
+#else
+#define FIPS_MODULE_VERSION UTS_RELEASE
+#endif
+
+static char fips_name[] = FIPS_MODULE_NAME;
+static char fips_version[] = FIPS_MODULE_VERSION;
+
+static const struct ctl_table crypto_sysctl_table[] = {
+	{
+		.procname	= "fips_enabled",
+		.data		= &fips_enabled,
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.proc_handler	= proc_dointvec
+	},
+	{
+		.procname	= "fips_name",
+		.data		= &fips_name,
+		.maxlen		= 64,
+		.mode		= 0444,
+		.proc_handler	= proc_dostring
+	},
+	{
+		.procname	= "fips_version",
+		.data		= &fips_version,
+		.maxlen		= 64,
+		.mode		= 0444,
+		.proc_handler	= proc_dostring
+	},
+};
+
+static struct ctl_table_header *crypto_sysctls;
+
+static void crypto_proc_fips_init(void)
+{
+	crypto_sysctls = register_sysctl("crypto", crypto_sysctl_table);
+}
+
+static void crypto_proc_fips_exit(void)
+{
+	unregister_sysctl_table(crypto_sysctls);
+}
+
+void fips_fail_notify(void)
+{
+	if (fips_enabled)
+		atomic_notifier_call_chain(&fips_fail_notif_chain, 0, NULL);
+}
+EXPORT_SYMBOL_GPL(fips_fail_notify);
+
+static int __init fips_init(void)
+{
+	crypto_proc_fips_init();
+	return 0;
+}
+
+static void __exit fips_exit(void)
+{
+	crypto_proc_fips_exit();
+}
+
+module_init(fips_init);
+module_exit(fips_exit);