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, 171 insertions, 0 deletions

diff --git a/fs/ntfs/debug.c b/fs/ntfs/debug.c
new file mode 100644
index 000000000..f241ebc97
--- /dev/null
+++ b/fs/ntfs/debug.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NTFS kernel debug support.
+ *
+ * Copyright (c) 2001-2004 Anton Altaparmakov
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include "debug.h"
+
+/*
+ * __ntfs_warning - output a warning to the syslog
+ * @function:	name of function outputting the warning
+ * @sb:		super block of mounted ntfs filesystem
+ * @fmt:	warning string containing format specifications
+ * @...:	a variable number of arguments specified in @fmt
+ *
+ * Outputs a warning to the syslog for the mounted ntfs filesystem described
+ * by @sb.
+ *
+ * @fmt and the corresponding @... is printf style format string containing
+ * the warning string and the corresponding format arguments, respectively.
+ *
+ * @function is the name of the function from which __ntfs_warning is being
+ * called.
+ *
+ * Note, you should be using debug.h::ntfs_warning(@sb, @fmt, @...) instead
+ * as this provides the @function parameter automatically.
+ */
+void __ntfs_warning(const char *function, const struct super_block *sb,
+		const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+	int flen = 0;
+
+	if (function)
+		flen = strlen(function);
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+#ifdef DEBUG
+	if (sb)
+		pr_warn("(device %s): %s(): %pV\n",
+			sb->s_id, flen ? function : "", &vaf);
+	else
+		pr_warn("%s(): %pV\n", flen ? function : "", &vaf);
+#else
+	if (sb)
+		pr_warn_ratelimited("(device %s): %s(): %pV\n",
+			sb->s_id, flen ? function : "", &vaf);
+	else
+		pr_warn_ratelimited("%s(): %pV\n", flen ? function : "", &vaf);
+#endif
+	va_end(args);
+}
+
+/*
+ * __ntfs_error - output an error to the syslog
+ * @function:	name of function outputting the error
+ * @sb:		super block of mounted ntfs filesystem
+ * @fmt:	error string containing format specifications
+ * @...:	a variable number of arguments specified in @fmt
+ *
+ * Outputs an error to the syslog for the mounted ntfs filesystem described
+ * by @sb.
+ *
+ * @fmt and the corresponding @... is printf style format string containing
+ * the error string and the corresponding format arguments, respectively.
+ *
+ * @function is the name of the function from which __ntfs_error is being
+ * called.
+ *
+ * Note, you should be using debug.h::ntfs_error(@sb, @fmt, @...) instead
+ * as this provides the @function parameter automatically.
+ */
+void __ntfs_error(const char *function, struct super_block *sb,
+		const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+	int flen = 0;
+
+	if (function)
+		flen = strlen(function);
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+#ifdef DEBUG
+	if (sb)
+		pr_err("(device %s): %s(): %pV\n",
+		       sb->s_id, flen ? function : "", &vaf);
+	else
+		pr_err("%s(): %pV\n", flen ? function : "", &vaf);
+#else
+	if (sb)
+		pr_err_ratelimited("(device %s): %s(): %pV\n",
+		       sb->s_id, flen ? function : "", &vaf);
+	else
+		pr_err_ratelimited("%s(): %pV\n", flen ? function : "", &vaf);
+#endif
+	va_end(args);
+
+	if (sb)
+		ntfs_handle_error(sb);
+}
+
+#ifdef DEBUG
+
+/* If 1, output debug messages, and if 0, don't. */
+int debug_msgs;
+
+void __ntfs_debug(const char *file, int line, const char *function,
+		const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+	int flen = 0;
+
+	if (!debug_msgs)
+		return;
+	if (function)
+		flen = strlen(function);
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	pr_debug("(%s, %d): %s(): %pV", file, line, flen ? function : "", &vaf);
+	va_end(args);
+}
+
+/* Dump a runlist. Caller has to provide synchronisation for @rl. */
+void ntfs_debug_dump_runlist(const struct runlist_element *rl)
+{
+	int i;
+	const char *lcn_str[5] = { "LCN_DELALLOC     ", "LCN_HOLE         ",
+				   "LCN_RL_NOT_MAPPED", "LCN_ENOENT       ",
+				   "LCN_unknown      " };
+
+	if (!debug_msgs)
+		return;
+	pr_debug("Dumping runlist (values in hex):\n");
+	if (!rl) {
+		pr_debug("Run list not present.\n");
+		return;
+	}
+	pr_debug("VCN              LCN               Run length\n");
+	for (i = 0; ; i++) {
+		s64 lcn = (rl + i)->lcn;
+
+		if (lcn < 0) {
+			int index = -lcn - 1;
+
+			if (index > -LCN_ENOENT - 1)
+				index = 3;
+			pr_debug("%-16Lx %s %-16Lx%s\n",
+					(long long)(rl + i)->vcn, lcn_str[index],
+					(long long)(rl + i)->length,
+					(rl + i)->length ? "" :
+						" (runlist end)");
+		} else
+			pr_debug("%-16Lx %-16Lx  %-16Lx%s\n",
+					(long long)(rl + i)->vcn,
+					(long long)(rl + i)->lcn,
+					(long long)(rl + i)->length,
+					(rl + i)->length ? "" :
+						" (runlist end)");
+		if (!(rl + i)->length)
+			break;
+	}
+}
+
+#endif